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

net/proxy/proxy_resolver_v8.h

-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// 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_PROXY_PROXY_RESOLVER_V8_H_
 #define NET_PROXY_PROXY_RESOLVER_V8_H_
 #pragma once
 
 #include "base/scoped_ptr.h"
 #include "net/proxy/proxy_resolver.h"
 
-class MessageLoop;
-
 namespace net {
 
-class HostResolver;
 class ProxyResolverJSBindings;
 
 // Implementation of ProxyResolver that uses V8 to evaluate PAC scripts.
 //
 // ----------------------------------------------------------------------------
 // !!! Important note on threading model:
 // ----------------------------------------------------------------------------
 // There can be only one instance of V8 running at a time. To enforce this
 // constraint, ProxyResolverV8 holds a v8::Locker during execution. Therefore
 // it is OK to run multiple instances of ProxyResolverV8 on different threads,
@@ skipping 39 matching lines @@
   scoped_ptr<Context> context_;
 
   scoped_ptr<ProxyResolverJSBindings> js_bindings_;
 
   DISALLOW_COPY_AND_ASSIGN(ProxyResolverV8);
 };
 
 }  // namespace net
 
 #endif  // NET_PROXY_PROXY_RESOLVER_V8_H_