Remove obviously unneeded forward declarations from headers under src/{app,base,net}.

net/http/http_network_layer.h

 // Copyright (c) 2010 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 NET_HTTP_HTTP_NETWORK_LAYER_H_
 #define NET_HTTP_HTTP_NETWORK_LAYER_H_
 #pragma once
 
 #include <string>
 
 #include "base/non_thread_safe.h"
 #include "base/ref_counted.h"
 #include "base/scoped_ptr.h"
 #include "net/http/http_transaction_factory.h"
 
 namespace net {
 
 class ClientSocketFactory;
 class HostResolver;
 class HttpAuthHandlerFactory;
 class HttpNetworkDelegate;
 class HttpNetworkSession;
 class NetLog;
-class ProxyInfo;
 class ProxyService;
 class SpdySessionPool;
 class SSLConfigService;
 
 class HttpNetworkLayer : public HttpTransactionFactory, public NonThreadSafe {
  public:
   // |socket_factory|, |proxy_service| and |host_resolver| must remain valid for
   // the lifetime of HttpNetworkLayer.
   HttpNetworkLayer(ClientSocketFactory* socket_factory,
                    HostResolver* host_resolver,
@@ skipping 68 matching lines @@
   HttpAuthHandlerFactory* http_auth_handler_factory_;
   HttpNetworkDelegate* network_delegate_;
   NetLog* net_log_;
 
   bool suspended_;
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_NETWORK_LAYER_H_