Use a direct include of strings headers in remoting/.

remoting/jingle_glue/iq_sender_unittest.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 "base/bind.h"
 #include "base/memory/ref_counted.h"
 #include "base/message_loop.h"
-#include "base/stringprintf.h"
+#include "base/strings/stringprintf.h"
 #include "remoting/jingle_glue/iq_sender.h"
 #include "remoting/jingle_glue/mock_objects.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/libjingle/source/talk/xmllite/xmlelement.h"
 #include "third_party/libjingle/source/talk/xmpp/constants.h"
 
 using ::testing::_;
 using ::testing::DeleteArg;
 using ::testing::InvokeWithoutArgs;
@@ skipping 132 matching lines @@
       QName("test:namespace", "response-body"));
   response->AddElement(result);
 
   EXPECT_TRUE(sender_->OnSignalStrategyIncomingStanza(response.get()));
 
   EXPECT_CALL(callback_, OnReply(request_.get(), XmlEq(response.get())));
   message_loop_.RunUntilIdle();
 }
 
 }  // namespace remoting