chrome: Cleanup class/struct forward declarations

chrome/browser/safe_browsing/safe_browsing_navigation_observer.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_H_
 #define CHROME_BROWSER_SAFE_BROWSING_SAFE_BROWSING_NAVIGATION_OBSERVER_H_
 
 #include "base/supports_user_data.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "url/gurl.h"
 
 namespace content {
 class NavigationHandle;
-struct ResourceRedirectDetails;
 }
 
 namespace safe_browsing {
 class SafeBrowsingNavigationObserverManager;
 
 // Struct to record the details of a navigation event for any frame.
 // This information will be used to fill |url_chain| field in safe browsing
 // download pings.
 struct NavigationEvent {
   NavigationEvent();
@@ skipping 80 matching lines @@
   bool has_user_gesture_;
 
   base::Time last_user_gesture_timestamp_;
 
   DISALLOW_COPY_AND_ASSIGN(SafeBrowsingNavigationObserver);
 };
 
 }  // namespace safe_browsing
 
 #endif  // CHROME_BROWSER_SAFE_BROWSING_SAFE_BROWSING_NAVIGATION_OBSERVER_H_