chrome: Cleanup class/struct forward declarations

chrome/browser/safe_browsing/safe_browsing_navigation_observer_manager.h

 // Copyright 2016 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_SAFE_BROWSING_SAFE_BROWSING_NAVIGATION_OBSERVER_MANAGER_H_
 #define CHROME_BROWSER_SAFE_BROWSING_SAFE_BROWSING_NAVIGATION_OBSERVER_MANAGER_H_
 
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "url/gurl.h"
 
-namespace content {
-class NavigationHandle;
-struct ResourceRedirectDetails;
-}
-
 namespace safe_browsing {
 
 class SafeBrowsingNavigationObserver;
 struct NavigationEvent;
 struct ResolvedIPAddress;
 
 // Manager class for SafeBrowsingNavigationObserver, which is in charge of
 // cleaning up stale navigation events, and identifing landing page/landing
 // referrer for a specific download.
 // TODO(jialiul): For now, SafeBrowsingNavigationObserverManager also listens to
@@ skipping 83 matching lines @@
   // in URLChainEntry in ClientDownloadRequest.
   HostToIpMap host_to_ip_map_;
 
   content::NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(SafeBrowsingNavigationObserverManager);
 };
 }  // namespace safe_browsing
 
 #endif  // CHROME_BROWSER_SAFE_BROWSING_SAFE_BROWSING_NAVIGATION_OBSERVER_MANAGER_H_