Fix bottom/right fixed-pos with non-overlay scrollbars.

cc/trees/layer_tree_impl.h

 // Copyright 2012 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_TREES_LAYER_TREE_IMPL_H_
 #define CC_TREES_LAYER_TREE_IMPL_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 85 matching lines @@
     source_frame_number_ = frame_number;
   }
 
   HeadsUpDisplayLayerImpl* hud_layer() { return hud_layer_; }
   void set_hud_layer(HeadsUpDisplayLayerImpl* layer_impl) {
     hud_layer_ = layer_impl;
   }
 
   LayerImpl* RootScrollLayer() const;
   LayerImpl* RootContainerLayer() const;
+  LayerImpl* ViewportLayer() const;
   LayerImpl* CurrentlyScrollingLayer() const;
+  int NonOverlayScrollbarThickness(ScrollbarOrientation orientation) const;
   void SetCurrentlyScrollingLayer(LayerImpl* layer);
   void ClearCurrentlyScrollingLayer();
 
   void FindRootScrollLayer();
   void UpdateMaxScrollOffset();
 
   SkColor background_color() const { return background_color_; }
   void set_background_color(SkColor color) { background_color_ = color; }
 
   bool has_transparent_background() const {
@@ skipping 122 matching lines @@
 
   ui::LatencyInfo latency_info_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(LayerTreeImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_IMPL_H_