Change Aura overlay scrollbars from solid color to painted scrollbars.

ui/native_theme/native_theme_base.h

 // 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.
 
 #ifndef UI_NATIVE_THEME_NATIVE_THEME_BASE_H_
 #define UI_NATIVE_THEME_NATIVE_THEME_BASE_H_
 
 #include <memory>
 
 #include "base/compiler_specific.h"
@@ skipping 133 matching lines @@
                                                   const gfx::Rect& rect) const {
   }
 
   // Shrinks checkbox/radio button rect, if necessary, to make room for padding
   // and drop shadow.
   // TODO(mohsen): This is needed because checkboxes/radio buttons on Android
   // have different padding from those on desktop Chrome. Get rid of this when
   // crbug.com/530746 is resolved.
   virtual void AdjustCheckboxRadioRectForPadding(SkRect* rect) const;
 
-  void set_scrollbar_button_length(unsigned int length) {
+  void set_scrollbar_button_length(int length) {
     scrollbar_button_length_ = length;
   }
   int scrollbar_button_length() const { return scrollbar_button_length_; }
 
   SkColor SaturateAndBrighten(SkScalar* hsv,
                               SkScalar saturate_amount,
                               SkScalar brighten_amount) const;
 
   // Paints the arrow used on the scrollbar and spinner.
   void PaintArrow(SkCanvas* canvas,
                   const gfx::Rect& rect,
                   Part direction,
                   SkColor color) const;
 
   // Returns the color used to draw the arrow.
   SkColor GetArrowColor(State state) const;
 
+  int scrollbar_width_;
+
  private:
   friend class NativeThemeAuraTest;
 
   SkPath PathForArrow(const gfx::Rect& rect, Part direction) const;
   gfx::Rect BoundingRectForArrow(const gfx::Rect& rect) const;
 
   void DrawVertLine(SkCanvas* canvas,
                     int x,
                     int y1,
                     int y2,
@@ skipping 12 matching lines @@
   SkColor OutlineColor(SkScalar* hsv1, SkScalar* hsv2) const;
 
   // Paint the common parts of the checkboxes and radio buttons.
   // borderRadius specifies how rounded the corners should be.
   SkRect PaintCheckboxRadioCommon(
       SkCanvas* canvas,
       State state,
       const gfx::Rect& rect,
       const SkScalar borderRadius) const;
 
-  unsigned int scrollbar_width_;
-
   // The length of the arrow buttons, 0 means no buttons are drawn.
-  unsigned int scrollbar_button_length_;
+  int scrollbar_button_length_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeThemeBase);
 };
 
 }  // namespace ui
 
 #endif  // UI_NATIVE_THEME_NATIVE_THEME_BASE_H_