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

net/http/http_auth_handler.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_AUTH_HANDLER_H_
 #define NET_HTTP_HTTP_AUTH_HANDLER_H_
 #pragma once
 
 #include <string>
 
 #include "base/string16.h"
 #include "base/time.h"
 #include "net/base/completion_callback.h"
 #include "net/base/net_log.h"
 #include "net/http/http_auth.h"
 
 class Histogram;
 
 namespace net {
 
-class HostResolver;
-class ProxyInfo;
 struct HttpRequestInfo;
 
 // HttpAuthHandler is the interface for the authentication schemes
 // (basic, digest, NTLM, Negotiate).
 // HttpAuthHandler objects are typically created by an HttpAuthHandlerFactory.
 class HttpAuthHandler {
  public:
   HttpAuthHandler();
   virtual ~HttpAuthHandler();
 
@@ skipping 144 matching lines @@
   CompletionCallback* original_callback_;
   CompletionCallbackImpl<HttpAuthHandler> wrapper_callback_;
   // When GenerateAuthToken was called.
   base::TimeTicks generate_auth_token_start_;
   scoped_refptr<Histogram> histogram_;
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_AUTH_HANDLER_H_