Reland r107720 - Enable the new layer animation framework.

ui/gfx/compositor/layer_animation_sequence.h

Index: ui/gfx/compositor/layer_animation_sequence.h
diff --git a/ui/gfx/compositor/layer_animation_sequence.h b/ui/gfx/compositor/layer_animation_sequence.h
index 87673d7676608deec1b574ca9bd6109967350803..4670587880cfd7a6e2316ced81138095f4f56524 100644
--- a/ui/gfx/compositor/layer_animation_sequence.h
+++ b/ui/gfx/compositor/layer_animation_sequence.h
@@ -37,6 +37,10 @@ class COMPOSITOR_EXPORT LayerAnimationSequence {
   // guaranteed that Animate will be called with elapsed = Duration().
   void 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.
+  void GetTargetValue(LayerAnimationElement::TargetValue* target) const;
+
   // Aborts the given animation.
   void Abort();