extensions: Cleanup class/struct fwd declarations

extensions/browser/guest_view/web_view/web_view_guest_delegate.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_WEB_VIEW_WEB_VIEW_GUEST_DELEGATE_H_
 #define EXTENSIONS_BROWSER_GUEST_VIEW_WEB_VIEW_WEB_VIEW_GUEST_DELEGATE_H_
 
 #include "base/callback.h"
 #include "components/guest_view/browser/guest_view_base.h"
 
 namespace extensions {
 
-namespace api {
-namespace web_view_internal {
-
-struct ContextMenuItem;
-}  // namespace web_view_internal
-}  // namespace api
-
 // A delegate class of WebViewGuest that are not a part of chrome.
 class WebViewGuestDelegate {
  public :
   virtual ~WebViewGuestDelegate() {}
 
   // Called when context menu operation was handled.
   virtual bool HandleContextMenu(const content::ContextMenuParams& params) = 0;
 
   // Called just after additional initialization is performed.
   virtual void OnDidInitialize() = 0;
 
   // Shows the context menu for the guest.
   virtual void OnShowContextMenu(int request_id) = 0;
 
   // Returns true if the WebViewGuest should handle find requests for its
   // embedder.
   virtual bool ShouldHandleFindRequestsForEmbedder() const = 0;
 
   virtual void SetContextMenuPosition(const gfx::Point& position) = 0;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_GUEST_VIEW_WEB_VIEW_WEB_VIEW_GUEST_DELEGATE_H_