Add explicit base namespace to string16 users.

chrome/common/extensions/extension_messages.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.
 
 // IPC messages for extensions.
 // Multiply-included message file, hence no include guard.
 
 #include <string>
 #include <vector>
 
@@ skipping 33 matching lines @@
   // Extra logging information.
   IPC_STRUCT_MEMBER(std::string, extra)
 IPC_STRUCT_END()
 
 // Parameters structure for ExtensionHostMsg_AddDOMActionToActivityLog.
 IPC_STRUCT_BEGIN(ExtensionHostMsg_DOMAction_Params)
   // URL of the page.
   IPC_STRUCT_MEMBER(GURL, url)
 
   // Title of the page.
-  IPC_STRUCT_MEMBER(string16, url_title)
+  IPC_STRUCT_MEMBER(base::string16, url_title)
 
   // API name.
   IPC_STRUCT_MEMBER(std::string, api_call)
 
   // List of arguments.
   IPC_STRUCT_MEMBER(base::ListValue, arguments)
 
   // Type of DOM API call.
   IPC_STRUCT_MEMBER(int, call_type)
 IPC_STRUCT_END()
@@ skipping 605 matching lines @@
 // Notifies the browser process that a tab has started or stopped matching
 // certain conditions.  This message is sent in response to several events:
 //
 // * ExtensionMsg_WatchPages was received, updating the set of conditions.
 // * A new page is loaded.  This will be sent after ViewHostMsg_FrameNavigate.
 //   Currently this only fires for the main frame.
 // * Something changed on an existing frame causing the set of matching searches
 //   to change.
 IPC_MESSAGE_ROUTED1(ExtensionHostMsg_OnWatchedPageChange,
                     std::vector<std::string> /* Matching CSS selectors */)