[Android]Optimization of scrollbar animation.

cc/layers/scrollbar_layer_impl_base.h

Index: cc/layers/scrollbar_layer_impl_base.h
diff --git a/cc/layers/scrollbar_layer_impl_base.h b/cc/layers/scrollbar_layer_impl_base.h
index 435943dfc4ce28bd1a555101faa27a0ff00f2888..7017ba258ec5ef456e22b5ecca411794d9c78da1 100644
--- a/cc/layers/scrollbar_layer_impl_base.h
+++ b/cc/layers/scrollbar_layer_impl_base.h
@@ -28,11 +28,11 @@ class CC_EXPORT ScrollbarLayerImplBase : public LayerImpl {
   void ClearClipLayer() { clip_layer_ = NULL; }
 
   float current_pos() const { return current_pos_; }
-  void SetCurrentPos(float current_pos);
+  bool SetCurrentPos(float current_pos);
   int maximum() const { return maximum_; }
-  void SetMaximum(int maximum);
+  bool SetMaximum(int maximum);
 
-  void SetVerticalAdjust(float vertical_adjust);
+  bool SetVerticalAdjust(float vertical_adjust);
 
   bool is_overlay_scrollbar() const { return is_overlay_scrollbar_; }
   void set_is_overlay_scrollbar(bool is_overlay) {
@@ -48,13 +48,13 @@ class CC_EXPORT ScrollbarLayerImplBase : public LayerImpl {
   virtual ScrollbarLayerImplBase* ToScrollbarLayer() OVERRIDE;
   void PushScrollClipPropertiesTo(LayerImpl* layer);
 
-  void SetVisibleToTotalLengthRatio(float ratio);
+  bool SetVisibleToTotalLengthRatio(float ratio);
   virtual gfx::Rect ComputeThumbQuadRect() const;
 
   float thumb_thickness_scale_factor() {
     return thumb_thickness_scale_factor_;
   }
-  void SetThumbThicknessScaleFactor(float thumb_thickness_scale_factor);
+  bool SetThumbThicknessScaleFactor(float thumb_thickness_scale_factor);
 
   void ScrollbarParametersDidChange();