Preemptively clear buffer reference if snapshot is unused

- Normally this will be picked up in the next GC, but there is no reason
  to wait

Bug: 129295298
Test: Manual
Change-Id: I945336e86d0980f926586cfba6327c8c6c142ce8

core/java/android/app/TaskStackListener.java

@@ -19,6 +19,7 @@ package android.app;
 import android.annotation.UnsupportedAppUsage;
 import android.app.ActivityManager.TaskSnapshot;
 import android.content.ComponentName;
+import android.os.Binder;
 import android.os.IBinder;
 import android.os.RemoteException;
 
@@ -155,6 +156,11 @@ public abstract class TaskStackListener extends ITaskStackListener.Stub {
     @Override
     @UnsupportedAppUsage
     public void onTaskSnapshotChanged(int taskId, TaskSnapshot snapshot) throws RemoteException {
+        if (Binder.getCallingPid() != android.os.Process.myPid()
+                && snapshot != null && snapshot.getSnapshot() != null) {
+            // Preemptively clear any reference to the buffer
+            snapshot.getSnapshot().destroy();
+        }
     }
 
     @Override

packages/SystemUI/shared/src/com/android/systemui/shared/system/TaskStackChangeListeners.java

@@ -70,6 +70,15 @@ public class TaskStackChangeListeners extends TaskStackListener {
 
     public void removeListener(TaskStackChangeListener listener) {
         mTaskStackListeners.remove(listener);
+        if (mTaskStackListeners.isEmpty() && mRegistered) {
+            // Unregister mTaskStackListener once we have no more listeners
+            try {
+                ActivityTaskManager.getService().unregisterTaskStackListener(this);
+                mRegistered = false;
+            } catch (Exception e) {
+                Log.w(TAG, "Failed to call unregisterTaskStackListener", e);
+            }
+        }
     }
 
     @Override