Make scroll offset type of float in cc

cc/animation/layer_animation_value_observer.h

Index: cc/animation/layer_animation_value_observer.h
diff --git a/cc/animation/layer_animation_value_observer.h b/cc/animation/layer_animation_value_observer.h
index e09180620f67a0dd4e4ad83b43df1678171547cd..420317ee8d035d3d1396b7d9b0ca3a499bfdaff6 100644
--- a/cc/animation/layer_animation_value_observer.h
+++ b/cc/animation/layer_animation_value_observer.h
@@ -9,6 +9,8 @@
 
 namespace cc {
 
+class ScrollOffset;
+
 class CC_EXPORT LayerAnimationValueObserver {
  public:
   virtual ~LayerAnimationValueObserver() {}
@@ -16,7 +18,8 @@ class CC_EXPORT LayerAnimationValueObserver {
   virtual void OnFilterAnimated(const FilterOperations& filters) = 0;
   virtual void OnOpacityAnimated(float opacity) = 0;
   virtual void OnTransformAnimated(const gfx::Transform& transform) = 0;
-  virtual void OnScrollOffsetAnimated(const gfx::Vector2dF& scroll_offset) = 0;
+  virtual void OnScrollOffsetAnimated(
+      const gfx::ScrollOffset& scroll_offset) = 0;
   virtual void OnAnimationWaitingForDeletion() = 0;
   virtual bool IsActive() const = 0;
 };
@@ -24,4 +27,3 @@ class CC_EXPORT LayerAnimationValueObserver {
 }  // namespace cc
 
 #endif  // CC_ANIMATION_LAYER_ANIMATION_VALUE_OBSERVER_H_
-