Allow CanvasSkia to bind to an existing SkCanvas.

ui/base/clipboard/clipboard_mac.mm

 // Copyright (c) 2011 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/base/clipboard/clipboard.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/file_path.h"
 #include "base/logging.h"
@@ skipping 240 matching lines @@
   if (!image.get())
     return SkBitmap();
 
   gfx::ScopedNSGraphicsContextSaveGState scoped_state;
   [image setFlipped:YES];
   int width = [image size].width;
   int height = [image size].height;
 
   gfx::CanvasSkia canvas(width, height, false);
   {
-    skia::ScopedPlatformPaint scoped_platform_paint(&canvas);
+    skia::ScopedPlatformPaint scoped_platform_paint(canvas.sk_canvas());
     CGContextRef gc = scoped_platform_paint.GetPlatformSurface();
     NSGraphicsContext* cocoa_gc =
         [NSGraphicsContext graphicsContextWithGraphicsPort:gc flipped:NO];
     [NSGraphicsContext setCurrentContext:cocoa_gc];
     [image drawInRect:NSMakeRect(0, 0, width, height)
              fromRect:NSZeroRect
             operation:NSCompositeCopy
              fraction:1.0];
   }
   return canvas.ExtractBitmap();
@@ skipping 106 matching lines @@
 }
 
 // static
 Clipboard::FormatType Clipboard::GetWebKitSmartPasteFormatType() {
   static const std::string type =
       base::SysNSStringToUTF8(kWebSmartPastePboardType);
   return type;
 }
 
 }  // namespace ui