Left side vertical MD scrollbars grow toward right.

cc/test/fake_scrollbar.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_TEST_FAKE_SCROLLBAR_H_
 #define CC_TEST_FAKE_SCROLLBAR_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "cc/input/scrollbar.h"
 #include "third_party/skia/include/core/SkColor.h"
 
 namespace cc {
 
 class FakeScrollbar : public Scrollbar {
  public:
   FakeScrollbar();
   FakeScrollbar(bool paint, bool has_thumb, bool is_overlay);
+  FakeScrollbar(bool paint,
+                bool has_thumb,
+                ScrollbarOrientation orientation,
+                bool is_left_side_vertical_scrollbar,
+                bool is_overlay);
   ~FakeScrollbar() override;
 
   // Scrollbar implementation.
   ScrollbarOrientation Orientation() const override;
   bool IsLeftSideVerticalScrollbar() const override;
   gfx::Point Location() const override;
   bool IsOverlay() const override;
   bool HasThumb() const override;
   int ThumbThickness() const override;
   int ThumbLength() const override;
@@ skipping 17 matching lines @@
   void set_needs_paint_thumb(bool needs_paint) {
     needs_paint_thumb_ = needs_paint;
   }
   void set_needs_paint_track(bool needs_paint) {
     needs_paint_track_ = needs_paint;
   }
 
  private:
   bool paint_;
   bool has_thumb_;
+  ScrollbarOrientation orientation_;
+  bool is_left_side_vertical_scrollbar_;
   bool is_overlay_;
   int thumb_thickness_;
   int thumb_length_;
   float thumb_opacity_;
   bool needs_paint_thumb_;
   bool needs_paint_track_;
   gfx::Point location_;
   gfx::Rect track_rect_;
   SkColor fill_color_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeScrollbar);
 };
 
 }  // namespace cc
 
 #endif  // CC_TEST_FAKE_SCROLLBAR_H_