Change GuestViewInternalCreateGuestFunction to create the guest view using the

extensions/browser/extension_function.h

 // Copyright 2013 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 EXTENSIONS_BROWSER_EXTENSION_FUNCTION_H_
 #define EXTENSIONS_BROWSER_EXTENSION_FUNCTION_H_
 
 #include <list>
 #include <string>
 
@@ skipping 425 matching lines @@
     dispatcher_ = dispatcher;
   }
   extensions::ExtensionFunctionDispatcher* dispatcher() const {
     return dispatcher_.get();
   }
 
   // Gets the "current" web contents if any. If there is no associated web
   // contents then defaults to the foremost one.
   virtual content::WebContents* GetAssociatedWebContents();
 
+  // Gets the visible web contents if any. In many cases this will be the same
+  // WebContents as |GetAssociatedWebContents|, however not always, in
+  // particular when the function caller is a background page.
+  virtual content::WebContents* GetVisibleWebContents();
+
  protected:
   // Emits a message to the extension's devtools console.
   void WriteToConsole(content::ConsoleMessageLevel level,
                       const std::string& message);
 
   friend struct content::BrowserThread::DeleteOnThread<
       content::BrowserThread::UI>;
   friend class base::DeleteHelper<UIThreadExtensionFunction>;
 
   virtual ~UIThreadExtensionFunction();
@@ skipping 149 matching lines @@
   virtual bool RunSync() = 0;
 
   // ValidationFailure override to match RunSync().
   static bool ValidationFailure(SyncIOThreadExtensionFunction* function);
 
  private:
   virtual ResponseAction Run() OVERRIDE;
 };
 
 #endif  // EXTENSIONS_BROWSER_EXTENSION_FUNCTION_H_