compositor: Tick the UI animations from cc, instead of from timer callbacks.

ui/aura/window.cc

Index: ui/aura/window.cc
diff --git a/ui/aura/window.cc b/ui/aura/window.cc
index b1e95c3f4739743c33a2f1858dcb716746dde5ce..000f4d2d2f160a1e3d6cf873fc1b7c1d9e4bef04 100644
--- a/ui/aura/window.cc
+++ b/ui/aura/window.cc
@@ -217,8 +217,10 @@ Window::Window(WindowDelegate* delegate)
 
 Window::~Window() {
   // |layer()| can be NULL during tests, or if this Window is layerless.
-  if (layer())
+  if (layer()) {
+    layer()->CompleteAllAnimations();

[ajuma, 2014/06/04 16:40:12]

I think we have cases where animations are expected to outlive the destruction
of the Window (the animation from http://crbug.com/341682 comes to mind as an
example). AIUI, in these cases the ownership of the animating layer is
transferred to an observer (like HidingWindowAnimationObserver) that destroys
the layer when the animation is completed.

[ajuma, 2014/06/04 17:13:12]

Sorry, that should be http://crbug.com/341862.

[sadrul, 2014/06/04 17:39:13]

For animating a window closing, we usually clone the layers first, and animate
them. The cloned layers becomes siblings to the original layers. So
destroying/stopping animations in the original layers do not affect the
animating cloned layers.

[ajuma, 2014/06/04 19:14:42]

Ah, things may have changed since the last time I was looking at the layer
cloning code (the cloning used to happen during OnWindowDestroying below, and
animations in progress before cloning were expected to continue). I'll defer to
sky@.

[sky, 2014/06/04 23:32:45]

I think you only want to do this if layer()->owner() == this. Otherwise someone
else owns the layer and presumably the animation should continue. Also, it would
be nice to have test coverage that animations are stopped.

[sadrul, 2014/06/05 01:03:36]

Done.
Done.

     layer()->SuppressPaint();
+  }
 
   // Let the delegate know we're in the processing of destroying.
   if (delegate_)