Skip drawing unsupported layers in forced software mode

cc/layers/scrollbar_layer_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_LAYERS_SCROLLBAR_LAYER_IMPL_H_
 #define CC_LAYERS_SCROLLBAR_LAYER_IMPL_H_
 
 #include "cc/base/cc_export.h"
 #include "cc/input/scrollbar.h"
 #include "cc/layers/layer_impl.h"
@@ skipping 52 matching lines @@
   }
   void set_visible_to_total_length_ratio(float ratio) {
     visible_to_total_length_ratio_ = ratio;
   }
 
   void SetCurrentPos(float current_pos) { current_pos_ = current_pos; }
   void SetMaximum(int maximum) { maximum_ = maximum; }
 
   gfx::Rect ComputeThumbQuadRect() const;
 
+  virtual bool CanDrawInTilelessSoftwareMode() const OVERRIDE;
+
  protected:
   ScrollbarLayerImpl(LayerTreeImpl* tree_impl,
                      int id,
                      ScrollbarOrientation orientation);
 
  private:
   virtual const char* LayerTypeAsString() const OVERRIDE;
 
   gfx::Rect ScrollbarLayerRectToContentRect(gfx::RectF layer_rect) const;
 
@@ skipping 20 matching lines @@
   bool is_scroll_view_scrollbar_;
   bool enabled_;
   bool is_custom_scrollbar_;
   bool is_overlay_scrollbar_;
 
   DISALLOW_COPY_AND_ASSIGN(ScrollbarLayerImpl);
 };
 
 }  // namespace cc
 #endif  // CC_LAYERS_SCROLLBAR_LAYER_IMPL_H_