content: Cleanup class/struct forward declarations

content/browser/frame_host/navigation_controller_delegate.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 CONTENT_BROWSER_FRAME_HOST_NAVIGATION_CONTROLLER_DELEGATE_H_
 #define CONTENT_BROWSER_FRAME_HOST_NAVIGATION_CONTROLLER_DELEGATE_H_
 
 #include <stdint.h>
 
 #include <string>
 #include "content/public/browser/invalidate_type.h"
 #include "content/public/browser/navigation_controller.h"
 #include "content/public/browser/navigation_details.h"
 
 namespace content {
 
 struct LoadCommittedDetails;
-struct LoadNotificationDetails;
-struct NativeWebKeyboardEvent;
 class FrameTree;
 class InterstitialPage;
 class InterstitialPageImpl;
 class RenderFrameHost;
 class RenderViewHost;
-class SiteInstance;
 class WebContents;
-class WebContentsDelegate;
 
 // Interface for objects embedding a NavigationController to provide the
 // functionality NavigationController needs.
 // TODO(nasko): This interface should exist for short amount of time, while
 // we transition navigation code from WebContents to Navigator.
 class NavigationControllerDelegate {
  public:
   virtual ~NavigationControllerDelegate() {}
 
   // Duplicates of WebContents methods.
@@ skipping 28 matching lines @@
       InterstitialPageImpl* interstitial_page) = 0;
   virtual void DidProceedOnInterstitial() = 0;
   virtual void DetachInterstitialPage() = 0;
 
   virtual void UpdateOverridingUserAgent() = 0;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_NAVIGATION_CONTROLLER_DELEGATE_H_