Attempt four at landing the "histogram.h removed from message_loop.h" patch.

net/proxy/proxy_service.cc

 // 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.
 
 #include "net/proxy/proxy_service.h"
 
 #include <algorithm>
 
 #include "base/compiler_specific.h"
 #include "base/logging.h"
+#include "base/histogram.h"
 #include "base/message_loop.h"
 #include "base/string_util.h"
 #include "googleurl/src/gurl.h"
 #include "net/base/forwarding_net_log.h"
 #include "net/base/net_log.h"
 #include "net/base/net_errors.h"
 #include "net/base/net_util.h"
 #include "net/proxy/init_proxy_resolver.h"
 #include "net/proxy/multi_threaded_proxy_resolver.h"
 #include "net/proxy/proxy_config_service_fixed.h"
@@ skipping 751 matching lines @@
     OnCompletion(result_);
   }
 }
 
 void SyncProxyServiceHelper::OnCompletion(int rv) {
   result_ = rv;
   event_.Signal();
 }
 
 }  // namespace net