Handle direction control in compositor Animations

cc/animation/animation.h

Index: cc/animation/animation.h
diff --git a/cc/animation/animation.h b/cc/animation/animation.h
index f996c38bbb3dd410bad69189955c8533a2b77e00..a34d01b5e5680c993e951bec51e336418131ba55 100644
--- a/cc/animation/animation.h
+++ b/cc/animation/animation.h
@@ -48,6 +48,8 @@ class CC_EXPORT Animation {
     TargetPropertyEnumSize
   };
 
+  enum Direction { Normal = 0, Reverse, Alternate, AlternateReverse };

[ajuma, 2014/03/04 19:02:38]

Is the "= 0" needed? (The previous enum only needs it because we want it to have
the same values as the corresponding blink enum.)

+
   static scoped_ptr<Animation> Create(scoped_ptr<AnimationCurve> curve,
                                       int animation_id,
                                       int group_id,
@@ -78,12 +80,8 @@ class CC_EXPORT Animation {
   void Suspend(double monotonic_time);
   void Resume(double monotonic_time);
 
-  // If alternates_direction is true, on odd numbered iterations we reverse the
-  // curve.
-  bool alternates_direction() const { return alternates_direction_; }
-  void set_alternates_direction(bool alternates) {
-    alternates_direction_ = alternates;
-  }
+  Direction direction() { return direction_; }
+  void set_direction(Direction direction) { direction_ = direction; }
 
   bool IsFinishedAt(double monotonic_time) const;
   bool is_finished() const {
@@ -150,7 +148,7 @@ class CC_EXPORT Animation {
   RunState run_state_;
   int iterations_;
   double start_time_;
-  bool alternates_direction_;
+  Direction direction_;
 
   // The time offset effectively pushes the start of the animation back in time.
   // This is used for resuming paused animations -- an animation is added with a