No need to kClear_Mode a layer right after its created, as that will automatically

chrome/browser/ui/views/frame/opaque_browser_frame_view.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 "chrome/browser/ui/views/frame/opaque_browser_frame_view.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 696 matching lines @@
   ui::ThemeProvider* tp = GetThemeProvider();
   gfx::ImageSkia* toolbar_left = tp->GetImageSkiaNamed(
       IDR_CONTENT_TOP_LEFT_CORNER);
   int bottom_edge_height = std::min(toolbar_left->height(), h) - split_point;
 
   // Split our canvas out so we can mask out the corners of the toolbar
   // without masking out the frame.
   canvas->SaveLayerAlpha(
       255, gfx::Rect(x - kClientEdgeThickness, y, w + kClientEdgeThickness * 3,
                      h));
-  canvas->sk_canvas()->drawARGB(0, 255, 255, 255, SkXfermode::kClear_Mode);
 
   // TODO(kuan): migrate background animation from cros to win by calling
   // GetToolbarBackgound* with the correct mode, refer to
   // BrowserNonClientFrameViewAsh.
   SkColor background_color = browser_view()->GetToolbarBackgroundColor(
       browser_view()->browser()->search_model()->mode().mode);
   gfx::ImageSkia* theme_toolbar = browser_view()->GetToolbarBackgroundImage(
       browser_view()->browser()->search_model()->mode().mode);
 
   // Paint the bottom rect.
@@ skipping 318 matching lines @@
 
 gfx::Rect OpaqueBrowserFrameView::CalculateClientAreaBounds(int width,
                                                             int height) const {
   int top_height = NonClientTopBorderHeight(false);
   int border_thickness = NonClientBorderThickness();
   return gfx::Rect(border_thickness, top_height,
                    std::max(0, width - (2 * border_thickness)),
                    std::max(0, height - GetReservedHeight() -
                        top_height - border_thickness));
 }