Fix unexpected closure of the bubble.

WindowManager calls ATMS#notifySingleTaskDisplayEmpty to notify that the
last task is removed from a single task display.

Originally it was called from ActivityStack when Tsak is removed, but
while merging ActivityStack and Task, CL[1] moved the call to Task. As a
result, the lister gets notification when ActivityRecord is removed,
instead of a last Task is removed, which causes unexpected bubble
closure.

[1]: Ifb167129c89a3aba11796daa21a9dee7200913ca

Bug: 157067689
Test: atest TaskStackChangedListnerTest
Change-Id: I93b745ba7fd1bb2fbef7915ddff2316100813187

3 files changed, 29 insertions, 11 deletions

diff --git a/services/core/java/com/android/server/wm/Task.java b/services/core/java/com/android/server/wm/Task.java
index 3ee7ee7a4276..ce2ae2a42069 100644
--- a/services/core/java/com/android/server/wm/Task.java
+++ b/services/core/java/com/android/server/wm/Task.java
@@ -1436,15 +1436,6 @@ class Task extends WindowContainer<WindowContainer> {
             mAtmService.getTaskChangeNotificationController().notifyTaskStackChanged();
         }
 
-        final boolean isRootTask = isRootTask();
-        if (isRootTask) {
-            final DisplayContent display = getDisplayContent();
-            if (display.isSingleTaskInstance()) {
-                mAtmService.notifySingleTaskDisplayEmpty(display.mDisplayId);
-            }
-            display.mDisplayContent.setLayoutNeeded();
-        }
-
         if (hasChild()) {
             updateEffectiveIntent();
 
@@ -1465,7 +1456,7 @@ class Task extends WindowContainer<WindowContainer> {
         } else if (!mReuseTask && !mCreatedByOrganizer) {
             // Remove entire task if it doesn't have any activity left and it isn't marked for reuse
             // or created by task organizer.
-            if (!isRootTask) {
+            if (!isRootTask()) {
                 getStack().removeChild(this, reason);
             }
             EventLogTags.writeWmTaskRemoved(mTaskId,
@@ -2817,6 +2808,10 @@ class Task extends WindowContainer<WindowContainer> {
         if (DEBUG_STACK) Slog.i(TAG, "removeTask: removing taskId=" + mTaskId);
         EventLogTags.writeWmTaskRemoved(mTaskId, "removeTask");
 
+        if (mDisplayContent != null && mDisplayContent.isSingleTaskInstance()) {
+            mAtmService.notifySingleTaskDisplayEmpty(mDisplayContent.mDisplayId);
+        }
+
         // If applicable let the TaskOrganizer know the Task is vanishing.
         setTaskOrganizer(null);
 
diff --git a/services/tests/wmtests/AndroidManifest.xml b/services/tests/wmtests/AndroidManifest.xml
index 30df0d4b4ad9..4040fa6a675e 100644
--- a/services/tests/wmtests/AndroidManifest.xml
+++ b/services/tests/wmtests/AndroidManifest.xml
@@ -54,6 +54,8 @@
         <activity android:name="com.android.server.wm.TaskStackChangedListenerTest$ActivityViewTestActivity" />
         <activity android:name="com.android.server.wm.TaskStackChangedListenerTest$ActivityInActivityView"
                   android:resizeableActivity="true" />
+        <activity android:name="com.android.server.wm.TaskStackChangedListenerTest$ActivityLaunchesNewActivityInActivityView"
+            android:resizeableActivity="true" />
         <activity android:name="com.android.server.wm.TaskStackChangedListenerTest$LandscapeActivity"
                   android:screenOrientation="sensorLandscape"
                   android:showWhenLocked="true"
diff --git a/services/tests/wmtests/src/com/android/server/wm/TaskStackChangedListenerTest.java b/services/tests/wmtests/src/com/android/server/wm/TaskStackChangedListenerTest.java
index 2c17bbeae498..2bd342420e2c 100644
--- a/services/tests/wmtests/src/com/android/server/wm/TaskStackChangedListenerTest.java
+++ b/services/tests/wmtests/src/com/android/server/wm/TaskStackChangedListenerTest.java
@@ -299,6 +299,20 @@ public class TaskStackChangedListenerTest {
         waitForCallback(singleTaskDisplayDrawnLatch);
     }
 
+    public static class ActivityLaunchesNewActivityInActivityView extends TestActivity {
+        private boolean mActivityBLaunched = false;
+
+        @Override
+        protected void onPostResume() {
+            super.onPostResume();
+            if (mActivityBLaunched) {
+                return;
+            }
+            mActivityBLaunched = true;
+            startActivity(new Intent(this, ActivityB.class));
+        }
+    }
+
     @Test
     public void testSingleTaskDisplayEmpty() throws Exception {
         final Instrumentation instrumentation = getInstrumentation();
@@ -335,13 +349,20 @@ public class TaskStackChangedListenerTest {
         });
         waitForCallback(activityViewReadyLatch);
 
+        // 1. start ActivityLaunchesNewActivityInActivityView in an ActivityView
+        // 2. ActivityLaunchesNewActivityInActivityView launches ActivityB
+        // 3. ActivityB finishes self.
+        // 4. Verify ITaskStackListener#onSingleTaskDisplayEmpty is not called yet.
         final Context context = instrumentation.getContext();
-        Intent intent = new Intent(context, ActivityInActivityView.class);
+        Intent intent = new Intent(context, ActivityLaunchesNewActivityInActivityView.class);
         intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_MULTIPLE_TASK);
         activityView.startActivity(intent);
         waitForCallback(singleTaskDisplayDrawnLatch);
+        UiDevice.getInstance(getInstrumentation()).waitForIdle();
         assertEquals(1, singleTaskDisplayEmptyLatch.getCount());
 
+        // 5. Release the container, and ActivityLaunchesNewActivityInActivityView finishes.
+        // 6. Verify ITaskStackListener#onSingleTaskDisplayEmpty is called.
         activityView.release();
         waitForCallback(activityViewDestroyedLatch);
         waitForCallback(singleTaskDisplayEmptyLatch);