Fix NPE when starting activity while no focused task

NexusLauncher was not started when FallbackHome finished itself
because activities was prevented to be resumed while display is
sleeping. So, NPE was thrown while starting an activity because
there was no focused task in the display since FallbackHome
activity was removed from the task and all tasks were also removed.

The activities should still be able to be resumed when calling
resumeTop methods explicitly (even when display is sleeping).

For the original issue of bubble activities, the activities in
secondary display can be prevented from starting by evaluating
keyguard-going-away state for default display only.

Bug: 164572568
Bug: 160338354
Bug: 168424696
Test: atest ActivityStackTests

Change-Id: Ica58b7e8c93e7aa688b335d1ecf7464bc8450e30
Merged-In: Ica58b7e8c93e7aa688b335d1ecf7464bc8450e30

5 files changed, 20 insertions, 32 deletions

diff --git a/services/core/java/com/android/server/wm/ActivityStack.java b/services/core/java/com/android/server/wm/ActivityStack.java
index cd508d0e1860..959aedcd1e4a 100644
--- a/services/core/java/com/android/server/wm/ActivityStack.java
+++ b/services/core/java/com/android/server/wm/ActivityStack.java
@@ -1990,7 +1990,7 @@ class ActivityStack extends Task {
         return mRootWindowContainer.resumeHomeActivity(prev, reason, getDisplayArea());
     }
 
-    void startActivityLocked(ActivityRecord r, ActivityRecord focusedTopActivity,
+    void startActivityLocked(ActivityRecord r, @Nullable ActivityRecord focusedTopActivity,
             boolean newTask, boolean keepCurTransition, ActivityOptions options) {
         Task rTask = r.getTask();
         final boolean allowMoveToFront = options == null || !options.getAvoidMoveToFront();
@@ -3336,7 +3336,11 @@ class ActivityStack extends Task {
         // Do not sleep activities in this stack if we're marked as focused and the keyguard
         // is in the process of going away.
         if (isFocusedStackOnDisplay()
-                && mStackSupervisor.getKeyguardController().isKeyguardGoingAway()) {
+                && mStackSupervisor.getKeyguardController().isKeyguardGoingAway()
+                // Avoid resuming activities on secondary displays since we don't want bubble
+                // activities to be resumed while bubble is still collapsed.
+                // TODO(b/113840485): Having keyguard going away state for secondary displays.
+                && display.isDefaultDisplay) {
             return false;
         }
 
diff --git a/services/core/java/com/android/server/wm/ActivityStarter.java b/services/core/java/com/android/server/wm/ActivityStarter.java
index b869eb56f536..a78232c05397 100644
--- a/services/core/java/com/android/server/wm/ActivityStarter.java
+++ b/services/core/java/com/android/server/wm/ActivityStarter.java
@@ -1697,8 +1697,9 @@ class ActivityStarter {
         mRootWindowContainer.sendPowerHintForLaunchStartIfNeeded(
                 false /* forceSend */, mStartActivity);
 
-        mTargetStack.startActivityLocked(mStartActivity, topStack.getTopNonFinishingActivity(),
-                newTask, mKeepCurTransition, mOptions);
+        mTargetStack.startActivityLocked(mStartActivity,
+                topStack != null ? topStack.getTopNonFinishingActivity() : null, newTask,
+                mKeepCurTransition, mOptions);
         if (mDoResume) {
             final ActivityRecord topTaskActivity =
                     mStartActivity.getTask().topRunningActivityLocked();
diff --git a/services/core/java/com/android/server/wm/RootWindowContainer.java b/services/core/java/com/android/server/wm/RootWindowContainer.java
index 049e46fb6cef..f57c9164a610 100644
--- a/services/core/java/com/android/server/wm/RootWindowContainer.java
+++ b/services/core/java/com/android/server/wm/RootWindowContainer.java
@@ -2305,10 +2305,6 @@ class RootWindowContainer extends WindowContainer<DisplayContent>
 
         for (int displayNdx = getChildCount() - 1; displayNdx >= 0; --displayNdx) {
             final DisplayContent display = getChildAt(displayNdx);
-            if (display.shouldSleep()) {
-                continue;
-            }
-
             boolean resumedOnDisplay = false;
             for (int tdaNdx = display.getTaskDisplayAreaCount() - 1; tdaNdx >= 0; --tdaNdx) {
                 final TaskDisplayArea taskDisplayArea = display.getTaskDisplayAreaAt(tdaNdx);
diff --git a/services/tests/wmtests/src/com/android/server/wm/ActivityStackTests.java b/services/tests/wmtests/src/com/android/server/wm/ActivityStackTests.java
index 1b42a0466cf7..e898c2573315 100644
--- a/services/tests/wmtests/src/com/android/server/wm/ActivityStackTests.java
+++ b/services/tests/wmtests/src/com/android/server/wm/ActivityStackTests.java
@@ -1206,19 +1206,22 @@ public class ActivityStackTests extends ActivityTestsBase {
     @Test
     public void testShouldSleepActivities() {
         // When focused activity and keyguard is going away, we should not sleep regardless
-        // of the display state
+        // of the display state, but keyguard-going-away should only take effects on default
+        // display since there is no keyguard on secondary displays (yet).
         verifyShouldSleepActivities(true /* focusedStack */, true /*keyguardGoingAway*/,
-                true /* displaySleeping */, false /* expected*/);
+                true /* displaySleeping */, true /* isDefaultDisplay */, false /* expected */);
+        verifyShouldSleepActivities(true /* focusedStack */, true /*keyguardGoingAway*/,
+                true /* displaySleeping */, false /* isDefaultDisplay */, true /* expected */);
 
         // When not the focused stack, defer to display sleeping state.
         verifyShouldSleepActivities(false /* focusedStack */, true /*keyguardGoingAway*/,
-                true /* displaySleeping */, true /* expected*/);
+                true /* displaySleeping */, true /* isDefaultDisplay */, true /* expected */);
 
         // If keyguard is going away, defer to the display sleeping state.
         verifyShouldSleepActivities(true /* focusedStack */, false /*keyguardGoingAway*/,
-                true /* displaySleeping */, true /* expected*/);
+                true /* displaySleeping */, true /* isDefaultDisplay */, true /* expected */);
         verifyShouldSleepActivities(true /* focusedStack */, false /*keyguardGoingAway*/,
-                false /* displaySleeping */, false /* expected*/);
+                false /* displaySleeping */, true /* isDefaultDisplay */, false /* expected */);
     }
 
     @Test
@@ -1428,9 +1431,11 @@ public class ActivityStackTests extends ActivityTestsBase {
     }
 
     private void verifyShouldSleepActivities(boolean focusedStack,
-            boolean keyguardGoingAway, boolean displaySleeping, boolean expected) {
+            boolean keyguardGoingAway, boolean displaySleeping, boolean isDefaultDisplay,
+            boolean expected) {
         final DisplayContent display = mock(DisplayContent.class);
         final KeyguardController keyguardController = mSupervisor.getKeyguardController();
+        display.isDefaultDisplay = isDefaultDisplay;
 
         doReturn(display).when(mStack).getDisplay();
         doReturn(keyguardGoingAway).when(keyguardController).isKeyguardGoingAway();
diff --git a/services/tests/wmtests/src/com/android/server/wm/RootActivityContainerTests.java b/services/tests/wmtests/src/com/android/server/wm/RootActivityContainerTests.java
index c848736a64c2..51db099676b0 100644
--- a/services/tests/wmtests/src/com/android/server/wm/RootActivityContainerTests.java
+++ b/services/tests/wmtests/src/com/android/server/wm/RootActivityContainerTests.java
@@ -896,24 +896,6 @@ public class RootActivityContainerTests extends ActivityTestsBase {
         assertEquals(taskDisplayArea.getTopStack(), taskDisplayArea.getRootHomeTask());
     }
 
-    @Test
-    public void testResumeFocusedStackOnSleepingDisplay() {
-        // Create an activity on secondary display.
-        final TestDisplayContent secondDisplay = addNewDisplayContentAt(
-                DisplayContent.POSITION_TOP);
-        final ActivityStack stack = secondDisplay.getDefaultTaskDisplayArea()
-                .createStack(WINDOWING_MODE_FULLSCREEN, ACTIVITY_TYPE_STANDARD, true /* onTop */);
-        final ActivityRecord activity = new ActivityBuilder(mService).setStack(stack).build();
-        spyOn(activity);
-        spyOn(stack);
-
-        // Cannot resumed activities on secondary display if the display should sleep.
-        doReturn(true).when(secondDisplay).shouldSleep();
-        mRootWindowContainer.resumeFocusedStacksTopActivities();
-        verify(stack, never()).resumeTopActivityUncheckedLocked(any(), any());
-        verify(activity, never()).makeActiveIfNeeded(any());
-    }
-
     /**
      * Mock {@link RootWindowContainer#resolveHomeActivity} for returning consistent activity
      * info for test cases.