Convert scroll offsets to use SyncedProperty.

cc/layers/layer.h

Index: cc/layers/layer.h
diff --git a/cc/layers/layer.h b/cc/layers/layer.h
index 017df68429956cc0065a7b98c9a4a7e713f24979..1dbb7c191f76c9b82c5c0082dd0c7a53a95e6793 100644
--- a/cc/layers/layer.h
+++ b/cc/layers/layer.h
@@ -311,10 +311,8 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
   void SetForceRenderSurface(bool force_render_surface);
   bool force_render_surface() const { return force_render_surface_; }
 
-  gfx::Vector2dF ScrollDelta() const { return gfx::Vector2dF(); }
-  gfx::ScrollOffset TotalScrollOffset() const {
-    return ScrollOffsetWithDelta(scroll_offset(), ScrollDelta());
-  }
+  gfx::ScrollOffset ScrollDelta() const { return gfx::ScrollOffset(); }
+  gfx::ScrollOffset CurrentScrollOffset() const { return scroll_offset_; }
 
   void SetDoubleSided(bool double_sided);
   bool double_sided() const { return double_sided_; }
@@ -599,7 +597,7 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
   void RemoveChildOrDependent(Layer* child);
 
   // LayerAnimationValueProvider implementation.
-  gfx::ScrollOffset ScrollOffsetForAnimation() const override;
+  gfx::ScrollOffset ScrollOffsetForAnimation() override;
 
   // LayerAnimationValueObserver implementation.
   void OnFilterAnimated(const FilterOperations& filters) override;