Allow the native theme to paint the corner between scrollbars

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 501 matching lines @@
                    midy - grippy_half_width,
                    midy + grippy_half_width,
                    paint);
     }
   }
 }
 
 void NativeThemeBase::PaintScrollbarCorner(SkCanvas* canvas,
                                            State state,
                                            const gfx::Rect& rect) const {
-  SkPaint paint;
-  paint.setColor(SK_ColorWHITE);
-  paint.setStyle(SkPaint::kFill_Style);
-  paint.setXfermodeMode(SkXfermode::kSrc_Mode);
-  canvas->drawIRect(RectToSkIRect(rect), paint);
 }
 
 void NativeThemeBase::PaintCheckbox(SkCanvas* canvas,
                                     State state,
                                     const gfx::Rect& rect,
                                     const ButtonExtraParams& button) const {
   SkRect skrect = PaintCheckboxRadioCommon(canvas, state, rect,
                                            SkIntToScalar(2));
   if (!skrect.isEmpty()) {
     // Draw the checkmark / dash.
@@ skipping 548 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