Work around a bug in an An app

An app has Animators (NoPauseAnimatorWrapper) that does not
check their listeners against null before cloning. The previous
implementation of AnimatorSet has masked this issue. But the
underlying bug should be fixed in this app.

For now, work around the bug by adding a listener to all the child
animators.

BUG: 34736819
Test: Manual

Change-Id: I968450aab62cf5d308e3b64e76dcf018178af67e

core/java/android/animation/AnimatorSet.java

@@ -174,6 +174,10 @@ public final class AnimatorSet extends Animator implements AnimationHandler.Anim
      */
     private long mPauseTime = -1;
 
+    // This is to work around a bug in b/34736819. This needs to be removed once play team
+    // fixes their side.
+    private AnimatorListenerAdapter mDummyListener = new AnimatorListenerAdapter() {};
+
     public AnimatorSet() {
         super();
         mNodeMap.put(mDelayAnim, mRootNode);
@@ -1018,6 +1022,8 @@ public final class AnimatorSet extends Animator implements AnimationHandler.Anim
     }
 
     private void startAnimation() {
+        addDummyListener();
+
         // Register animation callback
         addAnimationCallback(mStartDelay);
 
@@ -1062,6 +1068,20 @@ public final class AnimatorSet extends Animator implements AnimationHandler.Anim
         }
     }
 
+    // This is to work around the issue in b/34736819, as the old behavior in AnimatorSet had
+    // masked a real bug in play movies. TODO: remove this and below once the root cause is fixed.
+    private void addDummyListener() {
+        for (int i = 1; i < mNodes.size(); i++) {
+            mNodes.get(i).mAnimation.addListener(mDummyListener);
+        }
+    }
+
+    private void removeDummyListener() {
+        for (int i = 1; i < mNodes.size(); i++) {
+            mNodes.get(i).mAnimation.removeListener(mDummyListener);
+        }
+    }
+
     private int findLatestEventIdForTime(long currentPlayTime) {
         int size = mEvents.size();
         int latestId = mLastEventId;
@@ -1107,6 +1127,7 @@ public final class AnimatorSet extends Animator implements AnimationHandler.Anim
                 tmpListeners.get(i).onAnimationEnd(this, mReversing);
             }
         }
+        removeDummyListener();
         mSelfPulse = true;
         mReversing = false;
     }