chrome: Cleanup class/struct forward declarations

chrome/browser/apps/app_url_redirector.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 CHROME_BROWSER_APPS_APP_URL_REDIRECTOR_H_
 #define CHROME_BROWSER_APPS_APP_URL_REDIRECTOR_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "content/public/browser/navigation_throttle.h"
 
 namespace content {
 class NavigationHandle;
 class NavigationThrottle;
-class WebContents;
 }
 
 // This class creates navigation throttles that redirect URLs to apps that have
 // a matching URL handler in the 'url_handlers' manifest key. Note that this is
 // a UI thread class.
 class AppUrlRedirector {
  public:
   static std::unique_ptr<content::NavigationThrottle> MaybeCreateThrottleFor(
       content::NavigationHandle* handle);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(AppUrlRedirector);
 };
 
 #endif  // CHROME_BROWSER_APPS_APP_URL_REDIRECTOR_H_