Enable accelerated animations for orphaned layers

cc/layer_animation_controller.h

Index: cc/layer_animation_controller.h
diff --git a/cc/layer_animation_controller.h b/cc/layer_animation_controller.h
index 786887be39e9f1881479fa896df7bc5bf300b2f5..4c092d44cb0097cc01483a5ed6ca0ed83c019314 100644
--- a/cc/layer_animation_controller.h
+++ b/cc/layer_animation_controller.h
@@ -77,10 +77,13 @@ public:
     void setForceSync() { m_forceSync = true; }
 
     void setAnimationRegistrar(AnimationRegistrar*);
+    AnimationRegistrar* animationRegistrar() { return m_registrar; }
 
     void addObserver(LayerAnimationValueObserver*);
     void removeObserver(LayerAnimationValueObserver*);
 
+    bool hasNonOrphanedObserver();
+
 protected:
     friend class base::RefCounted<LayerAnimationController>;