Render aura scrollbars programmatically instead of with ninebox assets.

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 "base/command_line.h"
 #include "base/logging.h"
@@ skipping 155 matching lines @@
                                            double progress,
                                            const gfx::Rect& rect) const {
   if (rect.IsEmpty())
     return;
 
   // Currently state transition is animation only working for overlay scrollbars
   // on Aura platforms.
   switch (part) {
     case kScrollbarHorizontalThumb:
     case kScrollbarVerticalThumb:
-      PaintScrollbarThumbStateTransition(
-          canvas, startState, endState, progress, rect);
+      PaintScrollbarThumbStateTransition(canvas, part, startState, endState,
+                                         progress, rect);
       break;
     default:
       NOTREACHED() << "Does not support state transition for this part:"
                    << part;
       break;
   }
   return;
 }
 
 void NativeThemeBase::Paint(SkCanvas* canvas,
@@ skipping 847 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