[Extensions] Clean up the handling of ExtensionHostMsg_Request

extensions/browser/guest_view/extension_view/extension_view_guest_delegate.h

-// Copyright 2015 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_EXTENSION_VIEW_EXTENSION_VIEW_GUEST_DELEGATE_H_
-#define EXTENSIONS_BROWSER_GUEST_VIEW_EXTENSION_VIEW_EXTENSION_VIEW_GUEST_DELEGATE_H_
-
-#include "base/macros.h"
-
-namespace extensions {
-
-class ExtensionViewGuest;
-
-// Interface to handle communication between ExtensionViewGuest and
-// the browser.
-class ExtensionViewGuestDelegate {
- public:
-  explicit ExtensionViewGuestDelegate(ExtensionViewGuest* guest);
-  virtual ~ExtensionViewGuestDelegate();
-
-  // Called from ExtensionViewGuest::DidInitialize().
-  virtual void DidInitialize() = 0;
-
-  ExtensionViewGuest* extension_view_guest() const { return guest_; }
-
- private:
-  ExtensionViewGuest* const guest_;
-
-  DISALLOW_COPY_AND_ASSIGN(ExtensionViewGuestDelegate);
-};
-
-}  // namespace extensions
-
-#endif  // EXTENSIONS_BROWSER_GUEST_VIEW_EXTENSION_VIEW_EXTENSION_VIEW_GUEST_DELEGATE_H_