Prefix string16 with base:: in ui/.

ui/base/clipboard/custom_data_helper.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.
 //
 // TODO(dcheng): For efficiency reasons, consider passing custom data around
 // as a vector instead. It allows us to append a
-// std::pair<string16, string16> and swap the deserialized values in.
+// std::pair<base::string16, base::string16> and swap the deserialized values.
 
 #include "ui/base/clipboard/custom_data_helper.h"
 
 #include <utility>
 
 #include "base/pickle.h"
 
 namespace ui {
 
 namespace {
@@ skipping 102 matching lines @@
   for (std::map<base::string16, base::string16>::const_iterator it =
            data.begin();
        it != data.end();
        ++it) {
     pickle->WriteString16(it->first);
     pickle->WriteString16(it->second);
   }
 }
 
 }  // namespace ui