Update the remaining include paths of base/string_piece.h to its new location.

jingle/notifier/base/xmpp_connection.cc

 // 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.
 
 #include "jingle/notifier/base/xmpp_connection.h"
 
 #include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
-#include "base/string_piece.h"
+#include "base/strings/string_piece.h"
 #include "jingle/glue/chrome_async_socket.h"
 #include "jingle/glue/task_pump.h"
 #include "jingle/glue/xmpp_client_socket_factory.h"
 #include "jingle/notifier/base/weak_xmpp_client.h"
 #include "net/socket/client_socket_factory.h"
 #include "net/ssl/ssl_config_service.h"
 #include "net/url_request/url_request_context.h"
 #include "talk/xmpp/xmppclientsettings.h"
 
 namespace notifier {
@@ skipping 117 matching lines @@
 }
 
 void XmppConnection::ClearClient() {
   if (weak_xmpp_client_.get()) {
     weak_xmpp_client_->Invalidate();
     DCHECK(!weak_xmpp_client_.get());
   }
 }
 
 }  // namespace notifier