Revert 156318 - I had originally tried to build upon http://codereview.chromium.org/10869066/, but …

ui/compositor/layer_animation_sequence.h

Index: ui/compositor/layer_animation_sequence.h
===================================================================
--- ui/compositor/layer_animation_sequence.h	(revision 157564)
+++ ui/compositor/layer_animation_sequence.h	(working copy)
@@ -36,9 +36,9 @@
 
   // Updates the delegate to the appropriate value for |elapsed|, which is in
   // the range [0, Duration()].  If the animation is not aborted, it is
-  // guaranteed that Animate will be called with elapsed = Duration(). Requests
-  // a redraw if it is required.
-  void Progress(base::TimeDelta elapsed, LayerAnimationDelegate* delegate);
+  // guaranteed that Animate will be called with elapsed = Duration().
+  // Returns true if a redraw is required.
+  bool Progress(base::TimeDelta elapsed, LayerAnimationDelegate* delegate);
 
   // Sets the target value to the value that would have been set had
   // the sequence completed. Does nothing if the sequence is cyclic.