Change WebLayer::addAnimation to transfer ownership of WebAnimation.

public/platform/WebLayer.h

Index: public/platform/WebLayer.h
diff --git a/public/platform/WebLayer.h b/public/platform/WebLayer.h
index cedc299addc584a7689a49c7cc5d6f736c3179d8..c2c9fcbb5b7777977b376d98ba33f5687ec33d4c 100644
--- a/public/platform/WebLayer.h
+++ b/public/platform/WebLayer.h
@@ -136,7 +136,11 @@ public:
     // deleting the delegate.
     virtual void setAnimationDelegate(WebAnimationDelegate*) = 0;
 
+    // TODO(dshwang): temporary macro to change addAnimation() in both Blink and Chromium.
+#define ANIMATION_OWNERSHIP_TRANSFER
+
     // Returns false if the animation cannot be added.
+    // Takes ownership of the WebAnimation object.
     virtual bool addAnimation(WebAnimation*) = 0;
 
     // Removes all animations with the given id.