Add delegate to install web_contents helpers for MimeHandlerView.

extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.h

 // Copyright 2014 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_GUEST_VIEW_MIME_HANDLER_VIEW_MIME_HANDLER_VIEW_GUEST_H_
 #define EXTENSIONS_BROWSER_GUEST_VIEW_MIME_HANDLER_VIEW_MIME_HANDLER_VIEW_GUEST_H_
 
 #include "extensions/browser/guest_view/guest_view.h"
 
 namespace extensions {
 
+class MimeHandlerViewGuestDelegate;
+
 class MimeHandlerViewGuest : public GuestView<MimeHandlerViewGuest> {
  public:
   static GuestViewBase* Create(content::BrowserContext* browser_context,
                                int guest_instance_id);
 
   static const char Type[];
 
   // GuestViewBase implementation.
   virtual const char* GetAPINamespace() const OVERRIDE;
   virtual int GetTaskPrefix() const OVERRIDE;
   virtual void CreateWebContents(
       const std::string& embedder_extension_id,
       int embedder_render_process_id,
       const base::DictionaryValue& create_params,
       const WebContentsCreatedCallback& callback) OVERRIDE;
   virtual void DidAttachToEmbedder() OVERRIDE;
+  virtual void DidInitialize() OVERRIDE;
 
   // WebContentsDelegate implementation.
   virtual void HandleKeyboardEvent(
       content::WebContents* source,
       const content::NativeWebKeyboardEvent& event) OVERRIDE;
 
  private:
   MimeHandlerViewGuest(content::BrowserContext* browser_context,
                        int guest_instance_id);
   virtual ~MimeHandlerViewGuest();
 
+  scoped_ptr<MimeHandlerViewGuestDelegate> delegate_;
+
   DISALLOW_COPY_AND_ASSIGN(MimeHandlerViewGuest);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_GUEST_VIEW_MIME_HANDLER_VIEW_MIME_HANDLER_VIEW_GUEST_H_