Use nine-patch resource for drawing Aura overlay scrollbar thumb.

cc/test/fake_scrollbar.cc

 // 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.
 
 #include "cc/test/fake_scrollbar.h"
 
 #include "cc/paint/paint_flags.h"
 #include "ui/gfx/skia_util.h"
 
 namespace cc {
@@ skipping 73 matching lines @@
   flags.setColor(paint_fill_color());
   flags.setStyle(PaintFlags::kFill_Style);
 
   // Emulate the how the real scrollbar works by using scrollbar's rect for
   // TRACK and the given content_rect for the THUMB
   SkRect rect = part == TRACK ? RectToSkRect(TrackRect())
                               : RectToSkRect(content_rect);
   canvas->drawRect(rect, flags);
 }
 
+bool FakeScrollbar::UsesNinePatchThumbResource() const {
+  return false;
+}
+
+gfx::Size FakeScrollbar::NinePatchThumbCanvasSize() const {
+  return gfx::Size();
+}
+
+gfx::Rect FakeScrollbar::NinePatchThumbAperture() const {
+  return gfx::Rect();
+}
+
 }  // namespace cc