Handle direction control in compositor Animations

public/platform/WebCompositorAnimation.h

Index: public/platform/WebCompositorAnimation.h
diff --git a/public/platform/WebCompositorAnimation.h b/public/platform/WebCompositorAnimation.h
index e367d46a1fcbd398e02c0606f374e503dd840507..2150d804fa809fa62b3ef00612b5fd44a49a28b8 100644
--- a/public/platform/WebCompositorAnimation.h
+++ b/public/platform/WebCompositorAnimation.h
@@ -6,6 +6,7 @@
 #define WebCompositorAnimation_h
 
 #define WEB_ANIMATION_SUPPORTS_FRACTIONAL_ITERATIONS 1
+#define WEB_ANIMATION_SUPPORTS_FULL_DIRECTION 1
 
 namespace blink {
 
@@ -19,6 +20,13 @@ public:
         TargetPropertyScrollOffset
     };
 
+    enum Direction {
+        DirectionNormal = 0,
+        DirectionReverse,
+        DirectionAlternate,
+        DirectionAlternateReverse
+    };
+
     virtual ~WebCompositorAnimation() { }
 
     // An id is effectively the animation's name, and it is not unique.
@@ -38,9 +46,8 @@ public:
     virtual double timeOffset() const = 0;
     virtual void setTimeOffset(double monotonicTime) = 0;
 
-    // If alternatesDirection is true, on odd numbered iterations we reverse the curve.
-    virtual bool alternatesDirection() const = 0;
-    virtual void setAlternatesDirection(bool) = 0;
+    virtual Direction direction() const = 0;
+    virtual void setDirection(Direction) = 0;
 };
 
 } // namespace blink