Use a direct include of strings headers in content/browser/, part 2.

content/browser/worker_host/message_port_service.h

 // Copyright (c) 2012 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 CONTENT_BROWSER_WORKER_HOST_MESSAGE_PORT_SERVICE_H_
 #define CONTENT_BROWSER_WORKER_HOST_MESSAGE_PORT_SERVICE_H_
 
 #include <map>
 #include <utility>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/memory/singleton.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "ipc/ipc_message.h"
 
 namespace content {
 class WorkerMessageFilter;
 
 class MessagePortService {
  public:
   typedef std::vector<std::pair<string16, std::vector<int> > > QueuedMessages;
 
   // Returns the MessagePortService singleton.
@@ skipping 42 matching lines @@
 
   // We need globally unique identifiers for each message port.
   int next_message_port_id_;
 
   DISALLOW_COPY_AND_ASSIGN(MessagePortService);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WORKER_HOST_MESSAGE_PORT_SERVICE_H_