Fix Clipboard::ReadImage

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 229 matching lines @@
   // TODO(avi): src_url?
   if (src_url)
     src_url->clear();
 }
 
 SkBitmap Clipboard::ReadImage(Buffer buffer) const {
   DCHECK_EQ(buffer, BUFFER_STANDARD);
 
   scoped_nsobject<NSImage> image(
       [[NSImage alloc] initWithPasteboard:GetPasteboard()]);
-  if (image.get()) {
-    [image setFlipped:YES];
-    int width = [image size].width;
-    int height = [image size].height;
+  if (!image.get())
+    return SkBitmap();
 
-    gfx::CanvasSkia canvas(width, height, false);
+  [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);
     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];
     [NSGraphicsContext restoreGraphicsState];
-    return canvas.ExtractBitmap();
   }
-  return SkBitmap();
+  return canvas.ExtractBitmap();
 }
 
 void Clipboard::ReadBookmark(string16* title, std::string* url) const {
   NSPasteboard* pb = GetPasteboard();
 
   if (title) {
     NSString* contents = [pb stringForType:kUTTypeURLName];
     UTF8ToUTF16([contents UTF8String],
                 [contents lengthOfBytesUsingEncoding:NSUTF8StringEncoding],
                 title);
@@ skipping 96 matching lines @@
 }
 
 // static
 Clipboard::FormatType Clipboard::GetWebKitSmartPasteFormatType() {
   static const std::string type =
       base::SysNSStringToUTF8(kWebSmartPastePboardType);
   return type;
 }
 
 }  // namespace ui