Convert string16 to base::string16 in content.

content/public/plugin/content_plugin_client.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_PUBLIC_PLUGIN_CONTENT_PLUGIN_CLIENT_H_
 #define CONTENT_PUBLIC_PLUGIN_CONTENT_PLUGIN_CLIENT_H_
 
 #include "base/strings/string16.h"
 #include "content/public/common/content_client.h"
 
 namespace content {
 
 // Embedder API for participating in plugin logic.
 class CONTENT_EXPORT ContentPluginClient {
  public:
   virtual ~ContentPluginClient() {}
 
   // Called to perform any per-process initialization necessary before
   // the sandbox is initialized for the plugin process.
   virtual void PreSandboxInitialization() {}
 
   // Notifies that a plugin process has started.
-  virtual void PluginProcessStarted(const string16& plugin_name) {}
+  virtual void PluginProcessStarted(const base::string16& plugin_name) {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_PLUGIN_CONTENT_PLUGIN_CLIENT_H_