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

net/socket/socket_test_util.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_SOCKET_SOCKET_TEST_UTIL_H_
 #define NET_SOCKET_SOCKET_TEST_UTIL_H_
 #pragma once
 
 #include <cstring>
 #include <deque>
@@ skipping 27 matching lines @@
 enum {
   // A private network error code used by the socket test utility classes.
   // If the |result| member of a MockRead is
   // ERR_TEST_PEER_CLOSE_AFTER_NEXT_MOCK_READ, that MockRead is just a
   // marker that indicates the peer will close the connection after the next
   // MockRead.  The other members of that MockRead are ignored.
   ERR_TEST_PEER_CLOSE_AFTER_NEXT_MOCK_READ = -10000,
 };
 
 class ClientSocket;
-class HttpRequestHeaders;
-class HttpResponseHeaders;
 class MockClientSocket;
 class SSLClientSocket;
 
 struct MockConnect {
   // Asynchronous connection success.
   MockConnect() : async(true), result(OK) { }
   MockConnect(bool a, int r) : async(a), result(r) { }
 
   bool async;
   int result;
@@ skipping 804 matching lines @@
 
 extern const char kSOCKS5OkRequest[];
 extern const int kSOCKS5OkRequestLength;
 
 extern const char kSOCKS5OkResponse[];
 extern const int kSOCKS5OkResponseLength;
 
 }  // namespace net
 
 #endif  // NET_SOCKET_SOCKET_TEST_UTIL_H_