ios: Cleanup class/struct forward declarations

ios/web/net/request_tracker_impl.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 IOS_WEB_NET_REQUEST_TRACKER_IMPL_H_
 #define IOS_WEB_NET_REQUEST_TRACKER_IMPL_H_
 
 #import <Foundation/Foundation.h>
 #include <stdint.h>
 #include <map>
 #include <set>
 
 #include "base/callback_forward.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
 #import "ios/net/request_tracker.h"
 #import "ios/web/net/crw_request_tracker_delegate.h"
 #include "ios/web/public/web_thread.h"
 #include "net/url_request/url_request_context_getter.h"
 #include "url/gurl.h"
 
 @class SSLCarrier;
 @class CRWSSLCarrier;
 struct TrackerCounts;
 
-namespace content {
-struct SSLStatus;
-}
-
 namespace net {
 class HttpResponseHeaders;
 class URLRequest;
 class URLRequestContext;
 class SSLInfo;
 class X509Certificate;
 }
 
 namespace web {
 
@@ skipping 348 matching lines @@
   // Flag to synchronize deletion and callback creation. Lives on the IO thread.
   // True when this tracker has beed Close()d. If this is the case, no further
   // references to it should be generated (for example by binding it into a
   // callback), and the expectation is that it will soon be deleted.
   bool is_closing_;
 };
 
 }  // namespace web
 
 #endif  // IOS_WEB_NET_REQUEST_TRACKER_IMPL_H_