Refactor GuestViewContainer::AttachRequest to allow for other request types

extensions/renderer/guest_view/guest_view_container.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_RENDERER_GUEST_VIEW_GUEST_VIEW_CONTAINER_H_
 #define EXTENSIONS_RENDERER_GUEST_VIEW_GUEST_VIEW_CONTAINER_H_
 
 #include "content/public/renderer/browser_plugin_delegate.h"
 #include "content/public/renderer/render_frame_observer.h"
 #include "ipc/ipc_message.h"
 
 namespace extensions {
 
 class GuestViewContainer : public content::BrowserPluginDelegate,
                            public content::RenderFrameObserver {
  public:
   explicit GuestViewContainer(content::RenderFrame* render_frame);
   ~GuestViewContainer() override;
 
   // BrowserPluginDelegate implementation.
   void SetElementInstanceID(int element_instance_id) override;
 
   // RenderFrameObserver override.
   void OnDestruct() override;
   bool OnMessageReceived(const IPC::Message& message) override;
 
   virtual bool HandlesMessage(const IPC::Message& message) = 0;
   virtual bool OnMessage(const IPC::Message& message) = 0;
 
- protected:
   int element_instance_id() const { return element_instance_id_; }
   int render_view_routing_id() const { return render_view_routing_id_; }
 
  private:
   int element_instance_id_;
   int render_view_routing_id_;
 
   DISALLOW_COPY_AND_ASSIGN(GuestViewContainer);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_GUEST_VIEW_GUEST_VIEW_CONTAINER_H_