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

webkit/plugins/ppapi/ppapi_plugin_instance.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 WEBKIT_PLUGINS_PPAPI_PPAPI_PLUGIN_INSTANCE_H_
 #define WEBKIT_PLUGINS_PPAPI_PPAPI_PLUGIN_INSTANCE_H_
 
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "cc/layers/texture_layer_client.h"
 #include "googleurl/src/gurl.h"
 #include "ppapi/c/dev/pp_cursor_type_dev.h"
 #include "ppapi/c/dev/ppp_find_dev.h"
 #include "ppapi/c/dev/ppp_printing_dev.h"
 #include "ppapi/c/dev/ppp_selection_dev.h"
 #include "ppapi/c/dev/ppp_text_input_dev.h"
 #include "ppapi/c/dev/ppp_zoom_dev.h"
 #include "ppapi/c/pp_completion_callback.h"
 #include "ppapi/c/pp_instance.h"
@@ skipping 806 matching lines @@
   scoped_ptr<struct _NPP> npp_;
 
   friend class PpapiPluginInstanceTest;
   DISALLOW_COPY_AND_ASSIGN(PluginInstance);
 };
 
 }  // namespace ppapi
 }  // namespace webkit
 
 #endif  // WEBKIT_PLUGINS_PPAPI_PPAPI_PLUGIN_INSTANCE_H_