Use the asynchronous version of CopyFromBackingStore in CaptureVisibleTabFunction.

chrome/browser/extensions/extension_tabs_module.h

 // 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_TABS_MODULE_H__
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_TABS_MODULE_H__
 #pragma once
 
 #include <string>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "chrome/browser/extensions/extension_function.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "googleurl/src/gurl.h"
 
 class BackingStore;
 class Extension;
 class GURL;
 class SkBitmap;
 class TabContentsWrapper;
 namespace base {
 class DictionaryValue;
 }  // namespace base
 namespace content {
 class WebContents;
 }  // namespace content
+namespace skia {
+class PlatformCanvas;
+}  // namespace skia
 
 // Windows
 class GetWindowFunction : public SyncExtensionFunction {
   virtual ~GetWindowFunction() {}
   virtual bool RunImpl() OVERRIDE;
   DECLARE_EXTENSION_FUNCTION_NAME("windows.get")
 };
 class GetCurrentWindowFunction : public SyncExtensionFunction {
   virtual ~GetCurrentWindowFunction() {}
   virtual bool RunImpl() OVERRIDE;
@@ skipping 134 matching lines @@
 
   virtual ~CaptureVisibleTabFunction() {}
   virtual bool RunImpl() OVERRIDE;
   virtual bool GetTabToCapture(content::WebContents** web_contents,
                                TabContentsWrapper** wrapper);
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
   void SendResultFromBitmap(const SkBitmap& screen_capture);
 
+ private:
+  void CopyFromBackingStoreComplete(skia::PlatformCanvas* canvas,
+                                    bool succeeded);
+
   content::NotificationRegistrar registrar_;
 
   // The format (JPEG vs PNG) of the resulting image.  Set in RunImpl().
   ImageFormat image_format_;
 
   // Quality setting to use when encoding jpegs.  Set in RunImpl().
   int image_quality_;
 
   DECLARE_EXTENSION_FUNCTION_NAME("tabs.captureVisibleTab")
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_TABS_MODULE_H__