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

ui/native_theme/native_theme_base.cc

 // Copyright (c) 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.
 
 #include "ui/native_theme/native_theme_base.h"
 
 #include <limits>
 #include <memory>
 
 #include "base/command_line.h"
@@ skipping 224 matching lines @@
       NOTIMPLEMENTED();
       break;
     default:
       NOTREACHED() << "Unknown theme part: " << part;
       break;
   }
 
   canvas->restore();
 }
 
+bool NativeThemeBase::SupportsNinePatch(Part part) const {
+  return false;
+}
+
+gfx::Size NativeThemeBase::GetNinePatchCanvasSize(Part part) const {
+  NOTREACHED() << "NativeThemeBase doesn't support nine-patch resources.";
+  return gfx::Size();
+}
+
+gfx::Rect NativeThemeBase::GetNinePatchAperture(Part part) const {
+  NOTREACHED() << "NativeThemeBase doesn't support nine-patch resources.";
+  return gfx::Rect();
+}
+
 NativeThemeBase::NativeThemeBase()
     : scrollbar_width_(kDefaultScrollbarWidth),
       scrollbar_button_length_(kDefaultScrollbarButtonLength) {
 }
 
 NativeThemeBase::~NativeThemeBase() {
 }
 
 void NativeThemeBase::PaintArrowButton(
     SkCanvas* canvas,
@@ skipping 737 matching lines @@
   SkScalar min_diff = Clamp((hsv1[1] + hsv2[1]) * 1.2f, 0.28f, 0.5f);
   SkScalar diff = Clamp(fabs(hsv1[2] - hsv2[2]) / 2, min_diff, 0.5f);
 
   if (hsv1[2] + hsv2[2] > 1.0)
     diff = -diff;
 
   return SaturateAndBrighten(hsv2, -0.2f, diff);
 }
 
 }  // namespace ui