Cleanup swipe detector in case of double cancel

We manually dispatch cancel when returning to the previous state in
onDragEnd(), but could end in a bad state if getting a second,
external cancel (e.g. by pressing home). Thus, we restore the
onCancelListener after manually dispatching cancel.

Bug: 79258868
Change-Id: Idc4c33cede1d8af1829a4a744b9348d379bcf8f7

src/com/android/launcher3/anim/AnimatorPlaybackController.java

@@ -206,6 +206,10 @@ public abstract class AnimatorPlaybackController implements ValueAnimator.Animat
         mOnCancelRunnable = runnable;
     }
 
+    public Runnable getOnCancelRunnable() {
+        return mOnCancelRunnable;
+    }
+
     public static class AnimatorPlaybackControllerVL extends AnimatorPlaybackController {
 
         private final ValueAnimator[] mChildAnimations;