Merge "Add supplemental split protologs" into main

8 files changed, 205 insertions, 30 deletions

diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/common/split/DividerView.java b/libs/WindowManager/Shell/src/com/android/wm/shell/common/split/DividerView.java
index f801b0d01084..a87116ea4670 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/common/split/DividerView.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/common/split/DividerView.java
@@ -75,7 +75,6 @@ public class DividerView extends FrameLayout implements View.OnTouchListener {
     private SurfaceControlViewHost mViewHost;
     private DividerHandleView mHandle;
     private DividerRoundedCorner mCorners;
-    private View mBackground;
     private int mTouchElevation;
 
     private VelocityTracker mVelocityTracker;
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/common/split/SplitDecorManager.java b/libs/WindowManager/Shell/src/com/android/wm/shell/common/split/SplitDecorManager.java
index 2b1037711249..194eb47c9360 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/common/split/SplitDecorManager.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/common/split/SplitDecorManager.java
@@ -277,7 +277,7 @@ public class SplitDecorManager extends WindowlessWindowManager {
                 }
 
                 @Override
-                public void onAnimationEnd(@androidx.annotation.NonNull Animator animation) {
+                public void onAnimationEnd(@NonNull Animator animation) {
                     mRunningAnimationCount--;
                     animT.remove(mScreenshot);
                     animT.apply();
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/recents/RecentTasksController.java b/libs/WindowManager/Shell/src/com/android/wm/shell/recents/RecentTasksController.java
index e4213569b526..1c54754e9953 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/recents/RecentTasksController.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/recents/RecentTasksController.java
@@ -163,14 +163,14 @@ public class RecentTasksController implements TaskStackListenerCallback,
     /**
      * Adds a split pair. This call does not validate the taskIds, only that they are not the same.
      */
-    public void addSplitPair(int taskId1, int taskId2, SplitBounds splitBounds) {
+    public boolean addSplitPair(int taskId1, int taskId2, SplitBounds splitBounds) {
         if (taskId1 == taskId2) {
-            return;
+            return false;
         }
         if (mSplitTasks.get(taskId1, INVALID_TASK_ID) == taskId2
                 && mTaskSplitBoundsMap.get(taskId1).equals(splitBounds)) {
             // If the two tasks are already paired and the bounds are the same, then skip updating
-            return;
+            return false;
         }
         // Remove any previous pairs
         removeSplitPair(taskId1);
@@ -185,6 +185,7 @@ public class RecentTasksController implements TaskStackListenerCallback,
         notifyRecentTasksChanged();
         ProtoLog.v(ShellProtoLogGroup.WM_SHELL_RECENT_TASKS, "Add split pair: %d, %d, %s",
                 taskId1, taskId2, splitBounds);
+        return true;
     }
 
     /**
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/MainStage.java b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/MainStage.java
index e52235fda80f..64e26dbd70be 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/MainStage.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/MainStage.java
@@ -16,11 +16,14 @@
 
 package com.android.wm.shell.splitscreen;
 
+import static com.android.wm.shell.protolog.ShellProtoLogGroup.WM_SHELL_SPLIT_SCREEN;
+
 import android.content.Context;
 import android.view.SurfaceSession;
 import android.window.WindowContainerToken;
 import android.window.WindowContainerTransaction;
 
+import com.android.internal.protolog.common.ProtoLog;
 import com.android.launcher3.icons.IconProvider;
 import com.android.wm.shell.ShellTaskOrganizer;
 import com.android.wm.shell.common.SyncTransactionQueue;
@@ -50,6 +53,8 @@ class MainStage extends StageTaskListener {
 
     void activate(WindowContainerTransaction wct, boolean includingTopTask) {
         if (mIsActive) return;
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "activate: main stage includingTopTask=%b",
+                includingTopTask);
 
         if (includingTopTask) {
             reparentTopTask(wct);
@@ -64,6 +69,8 @@ class MainStage extends StageTaskListener {
 
     void deactivate(WindowContainerTransaction wct, boolean toTop) {
         if (!mIsActive) return;
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "deactivate: main stage toTop=%b rootTaskInfo=%s",
+                toTop, mRootTaskInfo);
         mIsActive = false;
 
         if (mRootTaskInfo == null) return;
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SideStage.java b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SideStage.java
index 9903113c5453..f5fbae55960a 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SideStage.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SideStage.java
@@ -16,12 +16,15 @@
 
 package com.android.wm.shell.splitscreen;
 
+import static com.android.wm.shell.protolog.ShellProtoLogGroup.WM_SHELL_SPLIT_SCREEN;
+
 import android.app.ActivityManager;
 import android.content.Context;
 import android.view.SurfaceSession;
 import android.window.WindowContainerToken;
 import android.window.WindowContainerTransaction;
 
+import com.android.internal.protolog.common.ProtoLog;
 import com.android.launcher3.icons.IconProvider;
 import com.android.wm.shell.ShellTaskOrganizer;
 import com.android.wm.shell.common.SyncTransactionQueue;
@@ -47,6 +50,8 @@ class SideStage extends StageTaskListener {
     }
 
     boolean removeAllTasks(WindowContainerTransaction wct, boolean toTop) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "remove all side stage tasks: childCount=%d toTop=%b",
+                mChildrenTaskInfo.size(), toTop);
         if (mChildrenTaskInfo.size() == 0) return false;
         wct.reparentTasks(
                 mRootTaskInfo.token,
@@ -59,6 +64,8 @@ class SideStage extends StageTaskListener {
 
     boolean removeTask(int taskId, WindowContainerToken newParent, WindowContainerTransaction wct) {
         final ActivityManager.RunningTaskInfo task = mChildrenTaskInfo.get(taskId);
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "remove side stage task: task=%d exists=%b", taskId,
+                task != null);
         if (task == null) return false;
         wct.reparent(task.token, newParent, false /* onTop */);
         return true;
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreenTransitions.java b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreenTransitions.java
index b60e361caad8..1d9fdeb92715 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreenTransitions.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreenTransitions.java
@@ -25,6 +25,8 @@ import static com.android.wm.shell.animation.Interpolators.ALPHA_IN;
 import static com.android.wm.shell.animation.Interpolators.ALPHA_OUT;
 import static com.android.wm.shell.common.split.SplitScreenConstants.FADE_DURATION;
 import static com.android.wm.shell.common.split.SplitScreenConstants.FLAG_IS_DIVIDER_BAR;
+import static com.android.wm.shell.protolog.ShellProtoLogGroup.WM_SHELL_SPLIT_SCREEN;
+import static com.android.wm.shell.protolog.ShellProtoLogGroup.WM_SHELL_TRANSITIONS;
 import static com.android.wm.shell.splitscreen.SplitScreen.stageTypeToString;
 import static com.android.wm.shell.splitscreen.SplitScreenController.EXIT_REASON_DRAG_DIVIDER;
 import static com.android.wm.shell.splitscreen.SplitScreenController.exitReasonToString;
@@ -101,6 +103,7 @@ class SplitScreenTransitions {
             @NonNull Transitions.TransitionFinishCallback finishCallback,
             @NonNull WindowContainerToken mainRoot, @NonNull WindowContainerToken sideRoot,
             @NonNull WindowContainerToken topRoot) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "playAnimation: transition=%d", info.getDebugId());
         initTransition(transition, finishTransaction, finishCallback);
 
         final TransitSession pendingTransition = getPendingTransition(transition);
@@ -123,10 +126,12 @@ class SplitScreenTransitions {
         playInternalAnimation(transition, info, startTransaction, mainRoot, sideRoot, topRoot);
     }
 
-    /** Internal funcation of playAnimation. */
+    /** Internal function of playAnimation. */
     private void playInternalAnimation(@NonNull IBinder transition, @NonNull TransitionInfo info,
             @NonNull SurfaceControl.Transaction t, @NonNull WindowContainerToken mainRoot,
             @NonNull WindowContainerToken sideRoot, @NonNull WindowContainerToken topRoot) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "playInternalAnimation: transition=%d",
+                info.getDebugId());
         // Play some place-holder fade animations
         final boolean isEnter = isPendingEnter(transition);
         for (int i = info.getChanges().size() - 1; i >= 0; --i) {
@@ -220,6 +225,8 @@ class SplitScreenTransitions {
             @NonNull Transitions.TransitionFinishCallback finishCallback,
             @NonNull WindowContainerToken toTopRoot, @NonNull SplitDecorManager toTopDecor,
             @NonNull WindowContainerToken topRoot) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "playDragDismissAnimation: transition=%d",
+                info.getDebugId());
         initTransition(transition, finishTransaction, finishCallback);
 
         for (int i = info.getChanges().size() - 1; i >= 0; --i) {
@@ -259,6 +266,7 @@ class SplitScreenTransitions {
             @NonNull Transitions.TransitionFinishCallback finishCallback,
             @NonNull WindowContainerToken mainRoot, @NonNull WindowContainerToken sideRoot,
             @NonNull SplitDecorManager mainDecor, @NonNull SplitDecorManager sideDecor) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "playResizeAnimation: transition=%d", info.getDebugId());
         initTransition(transition, finishTransaction, finishCallback);
 
         for (int i = info.getChanges().size() - 1; i >= 0; --i) {
@@ -312,13 +320,15 @@ class SplitScreenTransitions {
     @Nullable
     private TransitSession getPendingTransition(IBinder transition) {
         if (isPendingEnter(transition)) {
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "\tresolved enter transition");
             return mPendingEnter;
         } else if (isPendingDismiss(transition)) {
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "\tresolved dismiss transition");
             return mPendingDismiss;
         } else if (isPendingResize(transition)) {
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "\tresolved resize transition");
             return mPendingResize;
         }
-
         return null;
     }
 
@@ -339,7 +349,7 @@ class SplitScreenTransitions {
             Transitions.TransitionHandler handler,
             int extraTransitType, boolean resizeAnim) {
         if (mPendingEnter != null) {
-            ProtoLog.v(ShellProtoLogGroup.WM_SHELL_TRANSITIONS, "  splitTransition "
+            ProtoLog.v(WM_SHELL_TRANSITIONS, "  splitTransition "
                     + " skip to start enter split transition since it already exist. ");
             return null;
         }
@@ -355,8 +365,10 @@ class SplitScreenTransitions {
         mPendingEnter = new EnterSession(
                 transition, remoteTransition, extraTransitType, resizeAnim);
 
-        ProtoLog.v(ShellProtoLogGroup.WM_SHELL_TRANSITIONS, "  splitTransition "
+        ProtoLog.v(WM_SHELL_TRANSITIONS, "  splitTransition "
                 + " deduced Enter split screen");
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "setEnterTransition: transitType=%d resize=%b",
+                extraTransitType, resizeAnim);
     }
 
     /** Starts a transition to dismiss split. */
@@ -364,7 +376,7 @@ class SplitScreenTransitions {
             Transitions.TransitionHandler handler, @SplitScreen.StageType int dismissTop,
             @SplitScreenController.ExitReason int reason) {
         if (mPendingDismiss != null) {
-            ProtoLog.v(ShellProtoLogGroup.WM_SHELL_TRANSITIONS, "  splitTransition "
+            ProtoLog.v(WM_SHELL_TRANSITIONS, "  splitTransition "
                     + " skip to start dismiss split transition since it already exist. reason to "
                     + " dismiss = %s", exitReasonToString(reason));
             return null;
@@ -381,9 +393,11 @@ class SplitScreenTransitions {
             @SplitScreenController.ExitReason int reason) {
         mPendingDismiss = new DismissSession(transition, reason, dismissTop);
 
-        ProtoLog.v(ShellProtoLogGroup.WM_SHELL_TRANSITIONS, "  splitTransition "
+        ProtoLog.v(WM_SHELL_TRANSITIONS, "  splitTransition "
                         + " deduced Dismiss due to %s. toTop=%s",
                 exitReasonToString(reason), stageTypeToString(dismissTop));
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "setDismissTransition: reason=%s dismissTop=%s",
+                exitReasonToString(reason), stageTypeToString(dismissTop));
     }
 
     IBinder startResizeTransition(WindowContainerTransaction wct,
@@ -405,8 +419,9 @@ class SplitScreenTransitions {
             @Nullable TransitionConsumedCallback consumedCallback,
             @Nullable TransitionFinishedCallback finishCallback) {
         mPendingResize = new TransitSession(transition, consumedCallback, finishCallback);
-        ProtoLog.v(ShellProtoLogGroup.WM_SHELL_TRANSITIONS, "  splitTransition "
+        ProtoLog.v(WM_SHELL_TRANSITIONS, "  splitTransition "
                 + " deduced Resize split screen");
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "setResizeTransition");
     }
 
     void mergeAnimation(IBinder transition, TransitionInfo info, SurfaceControl.Transaction t,
@@ -444,12 +459,15 @@ class SplitScreenTransitions {
 
             mPendingEnter.onConsumed(aborted);
             mPendingEnter = null;
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onTransitionConsumed for enter transition");
         } else if (isPendingDismiss(transition)) {
             mPendingDismiss.onConsumed(aborted);
             mPendingDismiss = null;
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onTransitionConsumed for dismiss transition");
         } else if (isPendingResize(transition)) {
             mPendingResize.onConsumed(aborted);
             mPendingResize = null;
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onTransitionConsumed for resize transition");
         }
 
         // TODO: handle transition consumed for active remote handler
@@ -462,12 +480,15 @@ class SplitScreenTransitions {
         if (isPendingEnter(mAnimatingTransition)) {
             mPendingEnter.onFinished(wct, mFinishTransaction);
             mPendingEnter = null;
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onFinish for enter transition");
         } else if (isPendingDismiss(mAnimatingTransition)) {
             mPendingDismiss.onFinished(wct, mFinishTransaction);
             mPendingDismiss = null;
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onFinish for dismiss transition");
         } else if (isPendingResize(mAnimatingTransition)) {
             mPendingResize.onFinished(wct, mFinishTransaction);
             mPendingResize = null;
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onFinish for resize transition");
         }
 
         mActiveRemoteHandler = null;
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java
index 2933cf48614a..7a1595fdbf01 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java
@@ -44,6 +44,7 @@ import static com.android.wm.shell.common.split.SplitScreenConstants.SPLIT_POSIT
 import static com.android.wm.shell.common.split.SplitScreenConstants.splitPositionToString;
 import static com.android.wm.shell.common.split.SplitScreenUtils.reverseSplitPosition;
 import static com.android.wm.shell.common.split.SplitScreenUtils.splitFailureMessage;
+import static com.android.wm.shell.protolog.ShellProtoLogGroup.WM_SHELL_SPLIT_SCREEN;
 import static com.android.wm.shell.shared.TransitionUtil.isClosingType;
 import static com.android.wm.shell.shared.TransitionUtil.isOpeningType;
 import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_TYPE_MAIN;
@@ -138,6 +139,7 @@ import com.android.wm.shell.recents.RecentTasksController;
 import com.android.wm.shell.shared.TransitionUtil;
 import com.android.wm.shell.splitscreen.SplitScreen.StageType;
 import com.android.wm.shell.splitscreen.SplitScreenController.ExitReason;
+import com.android.wm.shell.splitscreen.SplitScreenController.SplitEnterReason;
 import com.android.wm.shell.transition.DefaultMixedHandler;
 import com.android.wm.shell.transition.LegacyTransitions;
 import com.android.wm.shell.transition.Transitions;
@@ -313,6 +315,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
 
         taskOrganizer.createRootTask(displayId, WINDOWING_MODE_FULLSCREEN, this /* listener */);
 
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "Creating main/side root task");
         mMainStage = new MainStage(
                 mContext,
                 mTaskOrganizer,
@@ -454,6 +457,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
 
     boolean moveToStage(ActivityManager.RunningTaskInfo task, @SplitPosition int stagePosition,
             WindowContainerTransaction wct) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "moveToStage: task=%d position=%d", task.taskId,
+                stagePosition);
         prepareEnterSplitScreen(wct, task, stagePosition, false /* resizeAnim */);
         if (ENABLE_SHELL_TRANSITIONS) {
             mSplitTransitions.startEnterTransition(TRANSIT_TO_FRONT, wct,
@@ -474,6 +479,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     }
 
     boolean removeFromSideStage(int taskId) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "removeFromSideStage: task=%d", taskId);
         final WindowContainerTransaction wct = new WindowContainerTransaction();
 
         /**
@@ -498,11 +504,15 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             enteredSplitSelect |= listener.onRequestEnterSplitSelect(taskInfo, splitPosition,
                     taskBounds);
         }
-        if (enteredSplitSelect) mTaskOrganizer.applyTransaction(wct);
+        if (enteredSplitSelect) {
+            mTaskOrganizer.applyTransaction(wct);
+        }
     }
 
     void startShortcut(String packageName, String shortcutId, @SplitPosition int position,
             Bundle options, UserHandle user) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "startShortcut: pkg=%s id=%s position=%d user=%d",
+                packageName, shortcutId, position, user.getIdentifier());
         final boolean isEnteringSplit = !isSplitActive();
 
         IRemoteAnimationRunner wrapper = new IRemoteAnimationRunner.Stub() {
@@ -564,6 +574,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
 
     /** Use this method to launch an existing Task via a taskId */
     void startTask(int taskId, @SplitPosition int position, @Nullable Bundle options) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "startTask: task=%d position=%d", taskId, position);
         mSplitRequest = new SplitRequest(taskId, position);
         final WindowContainerTransaction wct = new WindowContainerTransaction();
         options = resolveStartStage(STAGE_TYPE_UNDEFINED, position, options, null /* wct */);
@@ -595,6 +606,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     /** Launches an activity into split. */
     void startIntent(PendingIntent intent, Intent fillInIntent, @SplitPosition int position,
             @Nullable Bundle options) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "startIntent: intent=%s position=%d", intent.getIntent(),
+                position);
         mSplitRequest = new SplitRequest(intent.getIntent(), position);
         if (!ENABLE_SHELL_TRANSITIONS) {
             startIntentLegacy(intent, fillInIntent, position, options);
@@ -690,6 +703,9 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     void startTasks(int taskId1, @Nullable Bundle options1, int taskId2, @Nullable Bundle options2,
             @SplitPosition int splitPosition, @PersistentSnapPosition int snapPosition,
             @Nullable RemoteTransition remoteTransition, InstanceId instanceId) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN,
+                "startTasks: task1=%d task2=%d position=%d snapPosition=%d",
+                taskId1, taskId2, splitPosition, snapPosition);
         final WindowContainerTransaction wct = new WindowContainerTransaction();
         if (taskId2 == INVALID_TASK_ID) {
             if (mMainStage.containsTask(taskId1) || mSideStage.containsTask(taskId1)) {
@@ -718,6 +734,9 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             @Nullable Bundle options1, int taskId, @Nullable Bundle options2,
             @SplitPosition int splitPosition, @PersistentSnapPosition int snapPosition,
             @Nullable RemoteTransition remoteTransition, InstanceId instanceId) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN,
+                "startIntentAndTask: intent=%s task1=%d position=%d snapPosition=%d",
+                pendingIntent.getIntent(), taskId, splitPosition, snapPosition);
         final WindowContainerTransaction wct = new WindowContainerTransaction();
         if (taskId == INVALID_TASK_ID) {
             options1 = options1 != null ? options1 : new Bundle();
@@ -740,6 +759,9 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             int taskId, @Nullable Bundle options2, @SplitPosition int splitPosition,
             @PersistentSnapPosition int snapPosition, @Nullable RemoteTransition remoteTransition,
             InstanceId instanceId) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN,
+                "startShortcutAndTask: shortcut=%s task1=%d position=%d snapPosition=%d",
+                shortcutInfo, taskId, splitPosition, snapPosition);
         final WindowContainerTransaction wct = new WindowContainerTransaction();
         if (taskId == INVALID_TASK_ID) {
             options1 = options1 != null ? options1 : new Bundle();
@@ -801,6 +823,10 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             @Nullable ShortcutInfo shortcutInfo2, @Nullable Bundle options2,
             @SplitPosition int splitPosition, @PersistentSnapPosition int snapPosition,
             @Nullable RemoteTransition remoteTransition, InstanceId instanceId) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN,
+                "startIntents: intent1=%s intent2=%s position=%d snapPosition=%d",
+                pendingIntent1.getIntent(), pendingIntent2.getIntent(), splitPosition,
+                snapPosition);
         final WindowContainerTransaction wct = new WindowContainerTransaction();
         if (pendingIntent2 == null) {
             options1 = options1 != null ? options1 : new Bundle();
@@ -1302,6 +1328,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     }
 
     void switchSplitPosition(String reason) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "switchSplitPosition");
         final SurfaceControl.Transaction t = mTransactionPool.acquire();
         mTempRect1.setEmpty();
         final StageTaskListener topLeftStage =
@@ -1343,7 +1370,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
                     });
                 });
 
-        ProtoLog.v(ShellProtoLogGroup.WM_SHELL_SPLIT_SCREEN, "Switch split position: %s", reason);
+        ProtoLog.v(WM_SHELL_SPLIT_SCREEN, "Switch split position: %s", reason);
         mLogger.logSwap(getMainStagePosition(), mMainStage.getTopChildTaskUid(),
                 getSideStagePosition(), mSideStage.getTopChildTaskUid(),
                 mSplitLayout.isLeftRightSplit());
@@ -1376,11 +1403,12 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
         if (!mMainStage.isActive()) {
             return;
         }
-
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onKeyguardVisibilityChanged: showing=%b", showing);
         setDividerVisibility(!mKeyguardShowing, null);
     }
 
     void onFinishedWakingUp() {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onFinishedWakingUp");
         if (!mMainStage.isActive()) {
             return;
         }
@@ -1421,6 +1449,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     }
 
     void exitSplitScreen(int toTopTaskId, @ExitReason int exitReason) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "exitSplitScreen: topTaskId=%d reason=%s active=%b",
+                toTopTaskId, exitReasonToString(exitReason), mMainStage.isActive());
         if (!mMainStage.isActive()) return;
 
         StageTaskListener childrenToTop = null;
@@ -1439,6 +1469,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
 
     private void exitSplitScreen(@Nullable StageTaskListener childrenToTop,
             @ExitReason int exitReason) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "exitSplitScreen: mainStageToTop=%b reason=%s active=%b",
+                childrenToTop == mMainStage, exitReasonToString(exitReason), mMainStage.isActive());
         if (!mMainStage.isActive()) return;
 
         final WindowContainerTransaction wct = new WindowContainerTransaction();
@@ -1447,6 +1479,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
 
     private void applyExitSplitScreen(@Nullable StageTaskListener childrenToTop,
             WindowContainerTransaction wct, @ExitReason int exitReason) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "applyExitSplitScreen: reason=%s",
+                exitReasonToString(exitReason));
         if (!mMainStage.isActive() || mIsExiting) return;
 
         onSplitScreenExit();
@@ -1502,7 +1536,6 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             }
         });
 
-        Slog.i(TAG, "applyExitSplitScreen, reason = " + exitReasonToString(exitReason));
         // Log the exit
         if (childrenToTop != null) {
             logExitToStage(exitReason, childrenToTop == mMainStage);
@@ -1527,6 +1560,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
      * Exits the split screen by finishing one of the tasks.
      */
     protected void exitStage(@SplitPosition int stageToClose) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "exitStage: stageToClose=%d", stageToClose);
         mSplitLayout.flingDividerToDismiss(stageToClose == SPLIT_POSITION_BOTTOM_OR_RIGHT,
                 EXIT_REASON_APP_FINISHED);
     }
@@ -1540,12 +1574,13 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
         try {
             activityTaskManagerService.setFocusedTask(getTaskId(stageToFocus));
         } catch (RemoteException | NullPointerException e) {
-            ProtoLog.e(ShellProtoLogGroup.WM_SHELL_SPLIT_SCREEN,
+            ProtoLog.e(WM_SHELL_SPLIT_SCREEN,
                     "Unable to update focus on the chosen stage: %s", e.getMessage());
         }
     }
 
     private void clearRequestIfPresented() {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "clearRequestIfPresented");
         if (mSideStageListener.mVisible && mSideStageListener.mHasChildren
                 && mMainStageListener.mVisible && mSideStageListener.mHasChildren) {
             mSplitRequest = null;
@@ -1581,6 +1616,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     void clearSplitPairedInRecents(@ExitReason int exitReason) {
         if (!shouldBreakPairedTaskInRecents(exitReason) || !mShouldUpdateRecents) return;
 
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "clearSplitPairedInRecents: reason=%s",
+                exitReasonToString(exitReason));
         mRecentTasks.ifPresent(recentTasks -> {
             // Notify recents if we are exiting in a way that breaks the pair, and disable further
             // updates to splits in the recents until we enter split again
@@ -1597,11 +1634,13 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     void prepareExitSplitScreen(@StageType int stageToTop,
             @NonNull WindowContainerTransaction wct) {
         if (!mMainStage.isActive()) return;
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "prepareExitSplitScreen: stageToTop=%d", stageToTop);
         mSideStage.removeAllTasks(wct, stageToTop == STAGE_TYPE_SIDE);
         mMainStage.deactivate(wct, stageToTop == STAGE_TYPE_MAIN);
     }
 
     private void prepareEnterSplitScreen(WindowContainerTransaction wct) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "prepareEnterSplitScreen");
         prepareEnterSplitScreen(wct, null /* taskInfo */, SPLIT_POSITION_UNDEFINED,
                 !mIsDropEntering);
     }
@@ -1613,6 +1652,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     void prepareEnterSplitScreen(WindowContainerTransaction wct,
             @Nullable ActivityManager.RunningTaskInfo taskInfo, @SplitPosition int startPosition,
             boolean resizeAnim) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "prepareEnterSplitScreen: position=%d resize=%b",
+                startPosition, resizeAnim);
         onSplitScreenEnter();
         // Preemptively reset the reparenting behavior if we know that we are entering, as starting
         // split tasks with activity trampolines can inadvertently trigger the task to be
@@ -1629,6 +1670,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     private void prepareBringSplit(WindowContainerTransaction wct,
             @Nullable ActivityManager.RunningTaskInfo taskInfo, @SplitPosition int startPosition,
             boolean resizeAnim) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "prepareBringSplit: task=%d isSplitVisible=%b",
+                taskInfo != null ? taskInfo.taskId : -1, isSplitScreenVisible());
         if (taskInfo != null) {
             wct.startTask(taskInfo.taskId,
                     resolveStartStage(STAGE_TYPE_UNDEFINED, startPosition, null, wct));
@@ -1649,6 +1692,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     private void prepareActiveSplit(WindowContainerTransaction wct,
             @Nullable ActivityManager.RunningTaskInfo taskInfo, @SplitPosition int startPosition,
             boolean resizeAnim) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "prepareActiveSplit: task=%d isSplitVisible=%b",
+                taskInfo != null ? taskInfo.taskId : -1, isSplitScreenVisible());
         if (!ENABLE_SHELL_TRANSITIONS) {
             // Legacy transition we need to create divider here, shell transition case we will
             // create it on #finishEnterSplitScreen
@@ -1667,6 +1712,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     }
 
     private void prepareSplitLayout(WindowContainerTransaction wct, boolean resizeAnim) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "prepareSplitLayout: resize=%b", resizeAnim);
         if (resizeAnim) {
             mSplitLayout.setDividerAtBorder(mSideStagePosition == SPLIT_POSITION_TOP_OR_LEFT);
         } else {
@@ -1686,6 +1732,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     }
 
     void finishEnterSplitScreen(SurfaceControl.Transaction finishT) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "finishEnterSplitScreen");
         mSplitLayout.update(finishT, true /* resetImePosition */);
         mMainStage.getSplitDecorManager().inflate(mContext, mMainStage.mRootLeash,
                 getMainStageBounds());
@@ -1835,12 +1882,20 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
                     leftTopTaskId, rightBottomTaskId, mSplitLayout.calculateCurrentSnapPosition());
             if (mainStageTopTaskId != INVALID_TASK_ID && sideStageTopTaskId != INVALID_TASK_ID) {
                 // Update the pair for the top tasks
-                recentTasks.addSplitPair(mainStageTopTaskId, sideStageTopTaskId, splitBounds);
+                boolean added = recentTasks.addSplitPair(mainStageTopTaskId, sideStageTopTaskId,
+                        splitBounds);
+                if (added) {
+                    ProtoLog.d(WM_SHELL_SPLIT_SCREEN,
+                            "updateRecentTasksSplitPair: adding split pair ltTask=%d rbTask=%d",
+                            leftTopTaskId, rightBottomTaskId);
+                }
             }
         });
     }
 
     private void sendSplitVisibilityChanged() {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "sendSplitVisibilityChanged: dividerVisible=%b",
+                mDividerVisible);
         for (int i = mListeners.size() - 1; i >= 0; --i) {
             final SplitScreen.SplitScreenListener l = mListeners.get(i);
             l.onSplitVisibilityChanged(mDividerVisible);
@@ -1855,6 +1910,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             throw new IllegalArgumentException(this + "\n Unknown task appeared: " + taskInfo);
         }
 
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onTaskAppeared: task=%s", taskInfo);
         mRootTaskInfo = taskInfo;
         mRootTaskLeash = leash;
 
@@ -1880,6 +1936,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
         if (mSplitLayout != null
                 && mSplitLayout.updateConfiguration(mRootTaskInfo.configuration)
                 && mMainStage.isActive()) {
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onTaskInfoChanged: task=%d updating",
+                    taskInfo.taskId);
             // Clear the divider remote animating flag as the divider will be re-rendered to apply
             // the new rotation config.  Don't reset the IME state since those updates are not in
             // sync with task info changes.
@@ -1892,6 +1950,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     @Override
     @CallSuper
     public void onTaskVanished(ActivityManager.RunningTaskInfo taskInfo) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onTaskVanished: task=%s", taskInfo);
         if (mRootTaskInfo == null) {
             throw new IllegalArgumentException(this + "\n Unknown task vanished: " + taskInfo);
         }
@@ -1911,6 +1970,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
 
     @VisibleForTesting
     void onRootTaskAppeared() {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onRootTaskAppeared: rootTask=%s mainRoot=%b sideRoot=%b",
+                mRootTaskInfo, mMainStageListener.mHasRootTask, mSideStageListener.mHasRootTask);
         // Wait unit all root tasks appeared.
         if (mRootTaskInfo == null
                 || !mMainStageListener.mHasRootTask
@@ -1937,6 +1998,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
      * #onStageHasChildrenChanged because this would be called every time child task appeared.
      * NOTICE: This only be called on legacy transition. */
     private void onChildTaskAppeared(StageListenerImpl stageListener, int taskId) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onChildTaskAppeared: isMainStage=%b task=%d",
+                stageListener == mMainStageListener, taskId);
         // Handle entering split screen while there is a split pair running in the background.
         if (stageListener == mSideStageListener && !isSplitScreenVisible() && isSplitActive()
                 && mSplitRequest == null) {
@@ -1960,6 +2023,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     }
 
     private void onRootTaskVanished() {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onRootTaskVanished");
         final WindowContainerTransaction wct = new WindowContainerTransaction();
         mLaunchAdjacentController.clearLaunchAdjacentRoot();
         applyExitSplitScreen(null /* childrenToTop */, wct, EXIT_REASON_ROOT_TASK_VANISHED);
@@ -1990,6 +2054,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             return;
         }
 
+        // TODO Protolog
+
         // Check if it needs to dismiss split screen when both stage invisible.
         if (!mainStageVisible && mExitSplitScreenOnHide) {
             exitSplitScreen(null /* childrenToTop */, EXIT_REASON_RETURN_HOME);
@@ -2020,14 +2086,14 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             return;
         }
 
-        ProtoLog.d(ShellProtoLogGroup.WM_SHELL_SPLIT_SCREEN,
-                "Request to %s divider bar from %s.",
-                (visible ? "show" : "hide"), Debug.getCaller());
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN,
+                "setDividerVisibility: visible=%b keyguardShowing=%b dividerAnimating=%b caller=%s",
+                visible, mKeyguardShowing, mIsDividerRemoteAnimating, Debug.getCaller());
 
         // Defer showing divider bar after keyguard dismissed, so it won't interfere with keyguard
         // dismissing animation.
         if (visible && mKeyguardShowing) {
-            ProtoLog.d(ShellProtoLogGroup.WM_SHELL_SPLIT_SCREEN,
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN,
                     "   Defer showing divider bar due to keyguard showing.");
             return;
         }
@@ -2036,7 +2102,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
         sendSplitVisibilityChanged();
 
         if (mIsDividerRemoteAnimating) {
-            ProtoLog.d(ShellProtoLogGroup.WM_SHELL_SPLIT_SCREEN,
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN,
                     "   Skip animating divider bar due to it's remote animating.");
             return;
         }
@@ -2050,12 +2116,12 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     private void applyDividerVisibility(@Nullable SurfaceControl.Transaction t) {
         final SurfaceControl dividerLeash = mSplitLayout.getDividerLeash();
         if (dividerLeash == null) {
-            ProtoLog.d(ShellProtoLogGroup.WM_SHELL_SPLIT_SCREEN,
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN,
                     "   Skip animating divider bar due to divider leash not ready.");
             return;
         }
         if (mIsDividerRemoteAnimating) {
-            ProtoLog.d(ShellProtoLogGroup.WM_SHELL_SPLIT_SCREEN,
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN,
                     "   Skip animating divider bar due to it's remote animating.");
             return;
         }
@@ -2119,6 +2185,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     /** Callback when split roots have child or haven't under it.
      * NOTICE: This only be called on legacy transition. */
     private void onStageHasChildrenChanged(StageListenerImpl stageListener) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onStageHasChildrenChanged: isMainStage=%b",
+                stageListener == mMainStageListener);
         final boolean hasChildren = stageListener.mHasChildren;
         final boolean isSideStage = stageListener == mSideStageListener;
         if (!hasChildren && !mIsExiting && mMainStage.isActive()) {
@@ -2170,13 +2238,15 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     }
 
     @Override
-    public void onSnappedToDismiss(boolean bottomOrRight, int reason) {
+    public void onSnappedToDismiss(boolean bottomOrRight, @ExitReason int exitReason) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onSnappedToDismiss: bottomOrRight=%b reason=%s",
+                bottomOrRight, exitReasonToString(exitReason));
         final boolean mainStageToTop =
                 bottomOrRight ? mSideStagePosition == SPLIT_POSITION_BOTTOM_OR_RIGHT
                         : mSideStagePosition == SPLIT_POSITION_TOP_OR_LEFT;
         final StageTaskListener toTopStage = mainStageToTop ? mMainStage : mSideStage;
         if (!ENABLE_SHELL_TRANSITIONS) {
-            exitSplitScreen(toTopStage, reason);
+            exitSplitScreen(toTopStage, exitReason);
             return;
         }
 
@@ -2219,6 +2289,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
 
     @Override
     public void onLayoutSizeChanged(SplitLayout layout) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onLayoutSizeChanged");
         // Reset this flag every time onLayoutSizeChanged.
         mShowDecorImmediately = false;
 
@@ -2278,8 +2349,11 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
                 mSideStagePosition == SPLIT_POSITION_TOP_OR_LEFT ? mSideStage : mMainStage;
         final StageTaskListener bottomRightStage =
                 mSideStagePosition == SPLIT_POSITION_TOP_OR_LEFT ? mMainStage : mSideStage;
-        return layout.applyTaskChanges(wct, topLeftStage.mRootTaskInfo,
+        boolean updated = layout.applyTaskChanges(wct, topLeftStage.mRootTaskInfo,
                 bottomRightStage.mRootTaskInfo);
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "updateWindowBounds: topLeftStage=%s bottomRightStage=%s",
+                layout.getBounds1(), layout.getBounds2());
+        return updated;
     }
 
     void updateSurfaceBounds(@Nullable SplitLayout layout, @NonNull SurfaceControl.Transaction t,
@@ -2291,6 +2365,9 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
         (layout != null ? layout : mSplitLayout).applySurfaceChanges(t, topLeftStage.mRootLeash,
                 bottomRightStage.mRootLeash, topLeftStage.mDimLayer, bottomRightStage.mDimLayer,
                 applyResizingOffset);
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN,
+                "updateSurfaceBounds: topLeftStage=%s bottomRightStage=%s",
+                layout.getBounds1(), layout.getBounds2());
     }
 
     @Override
@@ -2329,6 +2406,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
 
     @Override
     public void setLayoutOffsetTarget(int offsetX, int offsetY, SplitLayout layout) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "setLayoutOffsetTarget: x=%d y=%d",
+                offsetX, offsetY);
         final StageTaskListener topLeftStage =
                 mSideStagePosition == SPLIT_POSITION_TOP_OR_LEFT ? mSideStage : mMainStage;
         final StageTaskListener bottomRightStage =
@@ -2343,6 +2422,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
         if (displayId != DEFAULT_DISPLAY) {
             return;
         }
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onDisplayAdded: display=%d", displayId);
         mDisplayController.addDisplayChangingController(this::onDisplayChange);
     }
 
@@ -2357,8 +2437,14 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
 
     private void onDisplayChange(int displayId, int fromRotation, int toRotation,
             @Nullable DisplayAreaInfo newDisplayAreaInfo, WindowContainerTransaction wct) {
-        if (displayId != DEFAULT_DISPLAY || !mMainStage.isActive()) return;
+        if (displayId != DEFAULT_DISPLAY || !mMainStage.isActive()) {
+            return;
+        }
 
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN,
+                "onDisplayChange: display=%d fromRot=%d toRot=%d config=%s",
+                displayId, fromRotation, toRotation,
+                newDisplayAreaInfo != null ? newDisplayAreaInfo.configuration : null);
         mSplitLayout.rotateTo(toRotation);
         if (newDisplayAreaInfo != null) {
             mSplitLayout.updateConfiguration(newDisplayAreaInfo.configuration);
@@ -2369,6 +2455,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
 
     @VisibleForTesting
     void onFoldedStateChanged(boolean folded) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onFoldedStateChanged: folded=%b", folded);
         mTopStageAfterFoldDismiss = STAGE_TYPE_UNDEFINED;
         if (!folded) return;
 
@@ -2439,6 +2526,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
         final ActivityManager.RunningTaskInfo triggerTask = request.getTriggerTask();
         if (triggerTask == null) {
             if (isSplitActive()) {
+                ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "handleRequest: transition=%d display rotation",
+                        request.getDebugId());
                 // Check if the display is rotating.
                 final TransitionRequestInfo.DisplayChange displayChange =
                         request.getDisplayChange();
@@ -2467,6 +2556,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
         }
 
         if (isSplitActive()) {
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "handleRequest: transition=%d split active",
+                    request.getDebugId());
             // Try to handle everything while in split-screen, so return a WCT even if it's empty.
             ProtoLog.v(ShellProtoLogGroup.WM_SHELL_TRANSITIONS, "  split is active so using split"
                             + "Transition to handle request. triggerTask=%d type=%s mainChildren=%d"
@@ -2541,6 +2632,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             return null;
         } else {
             if (isOpening && getStageOfTask(triggerTask) != null) {
+                ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "handleRequest: transition=%d enter split",
+                        request.getDebugId());
                 // One task is appearing into split, prepare to enter split screen.
                 out = new WindowContainerTransaction();
                 prepareEnterSplitScreen(out);
@@ -2557,6 +2650,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
      */
     public void addEnterOrExitIfNeeded(@Nullable TransitionRequestInfo request,
             @NonNull WindowContainerTransaction outWCT) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "addEnterOrExitIfNeeded: transition=%d",
+                request.getDebugId());
         final ActivityManager.RunningTaskInfo triggerTask = request.getTriggerTask();
         if (triggerTask != null && triggerTask.displayId != mDisplayId) {
             // Skip handling task on the other display.
@@ -2591,6 +2686,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     public void mergeAnimation(IBinder transition, TransitionInfo info,
             SurfaceControl.Transaction t, IBinder mergeTarget,
             Transitions.TransitionFinishCallback finishCallback) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "mergeAnimation: transition=%d", info.getDebugId());
         mSplitTransitions.mergeAnimation(transition, info, t, mergeTarget, finishCallback);
     }
 
@@ -2602,6 +2698,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     @Override
     public void onTransitionConsumed(@NonNull IBinder transition, boolean aborted,
             @Nullable SurfaceControl.Transaction finishT) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onTransitionConsumed");
         mSplitTransitions.onTransitionConsumed(transition, aborted, finishT);
     }
 
@@ -2617,6 +2714,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             // If we're not in split-mode, just abort so something else can handle it.
             if (!mMainStage.isActive()) return false;
 
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "startAnimation: transition=%d", info.getDebugId());
             mSplitLayout.setFreezeDividerWindow(false);
             final StageChangeRecord record = new StageChangeRecord();
             final int transitType = info.getType();
@@ -2727,6 +2825,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             if (mMixedHandler.animatePendingSplitWithDisplayChange(transition, info,
                     startTransaction, finishTransaction, finishCallback)) {
                 if (mSplitTransitions.isPendingResize(transition)) {
+                    ProtoLog.d(WM_SHELL_SPLIT_SCREEN,
+                            "startAnimation: transition=%d display change", info.getDebugId());
                     // Only need to update in resize because divider exist before transition.
                     mSplitLayout.update(startTransaction, true /* resetImePosition */);
                     startTransaction.apply();
@@ -2797,6 +2897,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             @NonNull SurfaceControl.Transaction startTransaction,
             @NonNull SurfaceControl.Transaction finishTransaction,
             @NonNull Transitions.TransitionFinishCallback finishCallback) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "startPendingAnimation: transition=%d",
+                info.getDebugId());
         boolean shouldAnimate = true;
         if (mSplitTransitions.isPendingEnter(transition)) {
             shouldAnimate = startPendingEnterAnimation(transition,
@@ -2830,6 +2932,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
 
     /** Called to clean-up state and do house-keeping after the animation is done. */
     public void onTransitionAnimationComplete() {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onTransitionAnimationComplete");
         // If still playing, let it finish.
         if (!mMainStage.isActive() && !mIsExiting) {
             // Update divider state after animation so that it is still around and positioned
@@ -2842,6 +2945,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             @NonNull SplitScreenTransitions.EnterSession enterTransition,
             @NonNull TransitionInfo info, @NonNull SurfaceControl.Transaction t,
             @NonNull SurfaceControl.Transaction finishT) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "startPendingEnterAnimation: enterTransition=%s",
+                enterTransition);
         // First, verify that we actually have opened apps in both splits.
         TransitionInfo.Change mainChild = null;
         TransitionInfo.Change sideChild = null;
@@ -2959,6 +3064,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     }
 
     public void goToFullscreenFromSplit() {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "goToFullscreenFromSplit");
         // If main stage is focused, toEnd = true if
         // mSideStagePosition = SPLIT_POSITION_BOTTOM_OR_RIGHT. Otherwise toEnd = false
         // If side stage is focused, toEnd = true if
@@ -2974,6 +3080,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
 
     /** Move the specified task to fullscreen, regardless of focus state. */
     public void moveTaskToFullscreen(int taskId, int exitReason) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "moveTaskToFullscreen");
         boolean leftOrTop;
         if (mMainStage.containsTask(taskId)) {
             leftOrTop = (mSideStagePosition == SPLIT_POSITION_TOP_OR_LEFT);
@@ -2994,6 +3101,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
      */
     public void onPipExpandToSplit(WindowContainerTransaction wct,
             ActivityManager.RunningTaskInfo taskInfo) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onPipExpandToSplit: task=%s", taskInfo);
         prepareEnterSplitScreen(wct, taskInfo, getActivateSplitPosition(taskInfo),
                 false /*resizeAnim*/);
 
@@ -3040,6 +3148,9 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     public void prepareDismissAnimation(@StageType int toStage, @ExitReason int dismissReason,
             @NonNull TransitionInfo info, @NonNull SurfaceControl.Transaction t,
             @NonNull SurfaceControl.Transaction finishT) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, 
+                "prepareDismissAnimation: transition=%d toStage=%d reason=%s",
+                info.getDebugId(), toStage, exitReasonToString(dismissReason));
         // Make some noise if things aren't totally expected. These states shouldn't effect
         // transitions locally, but remotes (like Launcher) may get confused if they were
         // depending on listener callbacks. This can happen because task-organizer callbacks
@@ -3126,6 +3237,9 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             @NonNull SplitScreenTransitions.DismissSession dismissTransition,
             @NonNull TransitionInfo info, @NonNull SurfaceControl.Transaction t,
             @NonNull SurfaceControl.Transaction finishT) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN,
+                "startPendingDismissAnimation: transition=%d dismissTransition=%s",
+                info.getDebugId(), dismissTransition);
         prepareDismissAnimation(dismissTransition.mDismissTop, dismissTransition.mReason, info,
                 t, finishT);
         if (dismissTransition.mDismissTop == STAGE_TYPE_UNDEFINED) {
@@ -3146,6 +3260,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
 
     /** Call this when starting the open-recents animation while split-screen is active. */
     public void onRecentsInSplitAnimationStart(TransitionInfo info) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onRecentsInSplitAnimationStart: transition=%d",
+                info.getDebugId());
         if (isSplitScreenVisible()) {
             // Cache tasks on live tile.
             for (int i = 0; i < info.getChanges().size(); ++i) {
@@ -3178,6 +3294,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     /** Call this when the recents animation during split-screen finishes. */
     public void onRecentsInSplitAnimationFinish(WindowContainerTransaction finishWct,
             SurfaceControl.Transaction finishT) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onRecentsInSplitAnimationFinish");
         mPausingTasks.clear();
         // Check if the recent transition is finished by returning to the current
         // split, so we can restore the divider bar.
@@ -3203,6 +3320,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
 
     /** Call this when the recents animation finishes by doing pair-to-pair switch. */
     public void onRecentsPairToPairAnimationFinish(WindowContainerTransaction finishWct) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onRecentsPairToPairAnimationFinish");
         // Pair-to-pair switch happened so here should evict the live tile from its stage.
         // Otherwise, the task will remain in stage, and occluding the new task when next time
         // user entering recents.
@@ -3284,6 +3402,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
      * handled.
      */
     private void setSplitsVisible(boolean visible) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "setSplitsVisible: visible=%b", visible);
         mMainStageListener.mVisible = mSideStageListener.mVisible = visible;
         mMainStageListener.mHasChildren = mSideStageListener.mHasChildren = visible;
     }
@@ -3292,6 +3411,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
      * Sets drag info to be logged when splitscreen is next entered.
      */
     public void onDroppedToSplit(@SplitPosition int position, InstanceId dragSessionId) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onDroppedToSplit: position=%d", position);
         if (!isSplitScreenVisible()) {
             mIsDropEntering = true;
             mSkipEvictingMainStageChildren = true;
@@ -3308,7 +3428,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     /**
      * Sets info to be logged when splitscreen is next entered.
      */
-    public void onRequestToSplit(InstanceId sessionId, int enterReason) {
+    public void onRequestToSplit(InstanceId sessionId, @SplitEnterReason int enterReason) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onRequestToSplit: reason=%d", enterReason);
         if (!isSplitScreenVisible() && !ENABLE_SHELL_TRANSITIONS) {
             // If split running background, exit split first.
             // Skip this on shell transition due to we could evict existing tasks on transition
@@ -3384,6 +3505,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
 
         @Override
         public void onNoLongerSupportMultiWindow(ActivityManager.RunningTaskInfo taskInfo) {
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onNoLongerSupportMultiWindow: task=%s", taskInfo);
             if (mMainStage.isActive()) {
                 final boolean isMainStage = mMainStageListener == this;
                 if (!ENABLE_SHELL_TRANSITIONS) {
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageTaskListener.java b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageTaskListener.java
index af7bf360f036..f33ab33dafcc 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageTaskListener.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageTaskListener.java
@@ -25,6 +25,7 @@ import static android.view.RemoteAnimationTarget.MODE_OPENING;
 import static com.android.wm.shell.common.split.SplitScreenConstants.CONTROLLED_ACTIVITY_TYPES;
 import static com.android.wm.shell.common.split.SplitScreenConstants.CONTROLLED_WINDOWING_MODES;
 import static com.android.wm.shell.common.split.SplitScreenConstants.CONTROLLED_WINDOWING_MODES_WHEN_ACTIVE;
+import static com.android.wm.shell.protolog.ShellProtoLogGroup.WM_SHELL_SPLIT_SCREEN;
 import static com.android.wm.shell.transition.Transitions.ENABLE_SHELL_TRANSITIONS;
 
 import android.annotation.CallSuper;
@@ -44,6 +45,7 @@ import android.window.WindowContainerTransaction;
 
 import androidx.annotation.NonNull;
 
+import com.android.internal.protolog.common.ProtoLog;
 import com.android.internal.util.ArrayUtils;
 import com.android.launcher3.icons.IconProvider;
 import com.android.wm.shell.ShellTaskOrganizer;
@@ -175,6 +177,9 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
     @Override
     @CallSuper
     public void onTaskAppeared(ActivityManager.RunningTaskInfo taskInfo, SurfaceControl leash) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onTaskAppeared: task=%d taskParent=%d rootTask=%d",
+                taskInfo.taskId, taskInfo.parentTaskId,
+                mRootTaskInfo != null ? mRootTaskInfo.taskId : -1);
         if (mRootTaskInfo == null) {
             mRootLeash = leash;
             mRootTaskInfo = taskInfo;
@@ -225,6 +230,9 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
                     || !ArrayUtils.contains(CONTROLLED_ACTIVITY_TYPES, taskInfo.getActivityType())
                     || !ArrayUtils.contains(CONTROLLED_WINDOWING_MODES_WHEN_ACTIVE,
                     taskInfo.getWindowingMode())) {
+                ProtoLog.d(WM_SHELL_SPLIT_SCREEN,
+                        "onTaskInfoChanged: task=%d no longer supports multiwindow",
+                        taskInfo.taskId);
                 // Leave split screen if the task no longer supports multi window or have
                 // uncontrolled task.
                 mCallbacks.onNoLongerSupportMultiWindow(taskInfo);
@@ -251,6 +259,7 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
     @Override
     @CallSuper
     public void onTaskVanished(ActivityManager.RunningTaskInfo taskInfo) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "onTaskVanished: task=%d", taskInfo.taskId);
         final int taskId = taskInfo.taskId;
         if (mRootTaskInfo.taskId == taskId) {
             mCallbacks.onRootTaskVanished();
@@ -333,6 +342,7 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
     }
 
     void addTask(ActivityManager.RunningTaskInfo task, WindowContainerTransaction wct) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "addTask: task=%d", task.taskId);
         // Clear overridden bounds and windowing mode to make sure the child task can inherit
         // windowing mode and bounds from split root.
         wct.setWindowingMode(task.token, WINDOWING_MODE_UNDEFINED)
@@ -342,6 +352,7 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
     }
 
     void reorderChild(int taskId, boolean onTop, WindowContainerTransaction wct) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "reorderChild: task=%d onTop=%b", taskId, onTop);
         if (!containsTask(taskId)) {
             return;
         }
@@ -357,6 +368,7 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
 
     /** Collects all the current child tasks and prepares transaction to evict them to display. */
     void evictAllChildren(WindowContainerTransaction wct) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "Evicting all children");
         for (int i = mChildrenTaskInfo.size() - 1; i >= 0; i--) {
             final ActivityManager.RunningTaskInfo taskInfo = mChildrenTaskInfo.valueAt(i);
             wct.reparent(taskInfo.token, null /* parent */, false /* onTop */);
@@ -367,11 +379,13 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
         for (int i = mChildrenTaskInfo.size() - 1; i >= 0; i--) {
             final ActivityManager.RunningTaskInfo taskInfo = mChildrenTaskInfo.valueAt(i);
             if (taskId == taskInfo.taskId) continue;
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "Evict other child: task=%d", taskId);
             wct.reparent(taskInfo.token, null /* parent */, false /* onTop */);
         }
     }
 
     void evictNonOpeningChildren(RemoteAnimationTarget[] apps, WindowContainerTransaction wct) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "evictNonOpeningChildren");
         final SparseArray<ActivityManager.RunningTaskInfo> toBeEvict = mChildrenTaskInfo.clone();
         for (int i = 0; i < apps.length; i++) {
             if (apps[i].mode == MODE_OPENING) {
@@ -380,6 +394,7 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
         }
         for (int i = toBeEvict.size() - 1; i >= 0; i--) {
             final ActivityManager.RunningTaskInfo taskInfo = toBeEvict.valueAt(i);
+            ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "Evict non-opening child: task=%d", taskInfo.taskId);
             wct.reparent(taskInfo.token, null /* parent */, false /* onTop */);
         }
     }
@@ -388,12 +403,15 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
         for (int i = mChildrenTaskInfo.size() - 1; i >= 0; i--) {
             final ActivityManager.RunningTaskInfo taskInfo = mChildrenTaskInfo.valueAt(i);
             if (!taskInfo.isVisible) {
+                ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "Evict invisible child: task=%d",
+                        taskInfo.taskId);
                 wct.reparent(taskInfo.token, null /* parent */, false /* onTop */);
             }
         }
     }
 
     void evictChildren(WindowContainerTransaction wct, int taskId) {
+        ProtoLog.d(WM_SHELL_SPLIT_SCREEN, "Evict child: task=%d", taskId);
         final ActivityManager.RunningTaskInfo taskInfo = mChildrenTaskInfo.get(taskId);
         if (taskInfo != null) {
             wct.reparent(taskInfo.token, null /* parent */, false /* onTop */);