Left side vertical MD scrollbars grow toward right.

cc/layers/painted_scrollbar_layer_impl.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_PAINTED_SCROLLBAR_LAYER_IMPL_H_
 #define CC_LAYERS_PAINTED_SCROLLBAR_LAYER_IMPL_H_
 
 #include "base/macros.h"
 #include "cc/base/cc_export.h"
 #include "cc/input/scrollbar.h"
 #include "cc/layers/scrollbar_layer_impl_base.h"
 #include "cc/resources/ui_resource_client.h"
 
 namespace cc {
 
 class LayerTreeImpl;
 class ScrollView;
 
 class CC_EXPORT PaintedScrollbarLayerImpl : public ScrollbarLayerImplBase {
  public:
-  static std::unique_ptr<PaintedScrollbarLayerImpl>
-  Create(LayerTreeImpl* tree_impl, int id, ScrollbarOrientation orientation);
+  static std::unique_ptr<PaintedScrollbarLayerImpl> Create(
+      LayerTreeImpl* tree_impl,
+      int id,
+      ScrollbarOrientation orientation,
+      bool is_left_side_vertical_scrollbar,
+      bool is_overlay);
   ~PaintedScrollbarLayerImpl() override;
 
   // LayerImpl implementation.
   std::unique_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl) override;
   void PushPropertiesTo(LayerImpl* layer) override;
 
   bool WillDraw(DrawMode draw_mode,
                 ResourceProvider* resource_provider) override;
   void AppendQuads(RenderPass* render_pass,
                    AppendQuadsData* append_quads_data) override;
@@ skipping 15 matching lines @@
 
   void set_internal_contents_scale_and_bounds(float content_scale,
                                               const gfx::Size& content_bounds) {
     internal_contents_scale_ = content_scale;
     internal_content_bounds_ = content_bounds;
   }
 
  protected:
   PaintedScrollbarLayerImpl(LayerTreeImpl* tree_impl,
                             int id,
-                            ScrollbarOrientation orientation);
+                            ScrollbarOrientation orientation,
+                            bool is_left_side_vertical_scrollbar,
+                            bool is_overlay);
 
   // ScrollbarLayerImplBase implementation.
   int ThumbThickness() const override;
   int ThumbLength() const override;
   float TrackLength() const override;
   int TrackStart() const override;
   bool IsThumbResizable() const override;
 
  private:
   const char* LayerTypeAsString() const override;
 
   UIResourceId track_ui_resource_id_;
   UIResourceId thumb_ui_resource_id_;
 
   float thumb_opacity_;
 
   float internal_contents_scale_;
   gfx::Size internal_content_bounds_;
 
   int thumb_thickness_;
   int thumb_length_;
   int track_start_;
   int track_length_;
 
   DISALLOW_COPY_AND_ASSIGN(PaintedScrollbarLayerImpl);
 };
 
 }  // namespace cc
 #endif  // CC_LAYERS_PAINTED_SCROLLBAR_LAYER_IMPL_H_