[Android]Optimization of scrollbar animation.

cc/layers/scrollbar_layer_impl_base.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_LAYERS_SCROLLBAR_LAYER_IMPL_BASE_H_
 #define CC_LAYERS_SCROLLBAR_LAYER_IMPL_BASE_H_
 
 #include "cc/base/cc_export.h"
 #include "cc/input/scrollbar.h"
 #include "cc/layers/layer.h"
@@ skipping 10 matching lines @@
   }
   int ClipLayerId() const {
     return clip_layer_ ? clip_layer_->id() : Layer::INVALID_ID;
   }
 
   void SetScrollLayerAndClipLayerByIds(int scroll_layer_id, int clip_layer_id);
   void ClearScrollLayer() { scroll_layer_ = NULL; }
   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) {
     is_overlay_scrollbar_ = is_overlay;
   }
 
   ScrollbarOrientation orientation() const { return orientation_; }
   bool is_left_side_vertical_scrollbar() {
     return is_left_side_vertical_scrollbar_;
   }
 
   virtual void PushPropertiesTo(LayerImpl* layer) OVERRIDE;
   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();
 
  protected:
   ScrollbarLayerImplBase(LayerTreeImpl* tree_impl,
                          int id,
                          ScrollbarOrientation orientation,
                          bool is_left_side_vertical_scrollbar,
                          bool is_overlay);
   virtual ~ScrollbarLayerImplBase();
@@ skipping 29 matching lines @@
   float vertical_adjust_;
 
   float visible_to_total_length_ratio_;
 
   DISALLOW_COPY_AND_ASSIGN(ScrollbarLayerImplBase);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_SCROLLBAR_LAYER_IMPL_BASE_H_