Add base:: to string16s in chrome/.

chrome/installer/util/uninstall_metrics.h

 // Copyright 2013 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 CHROME_INSTALLER_UTIL_UNINSTALL_METRICS_H_
 #define CHROME_INSTALLER_UTIL_UNINSTALL_METRICS_H_
 
 #include "base/strings/string16.h"
 
 namespace base {
 class DictionaryValue;
 class FilePath;
 }
 
 namespace installer {
 
 // Extracts uninstall metrics from the given JSON value.
 bool ExtractUninstallMetrics(const base::DictionaryValue& root,
-                             string16* uninstall_metrics);
+                             base::string16* uninstall_metrics);
 
 // Extracts uninstall metrics from the JSON file located at file_path.
 // Returns them in a form suitable for appending to a url that already
 // has GET parameters, i.e. &metric1=foo&metric2=bar.
 // Returns true if uninstall_metrics has been successfully populated with
 // the uninstall metrics, false otherwise.
 bool ExtractUninstallMetricsFromFile(const base::FilePath& file_path,
-                                     string16* uninstall_metrics);
+                                     base::string16* uninstall_metrics);
 
 }  // namespace installer
 
 #endif  // CHROME_INSTALLER_UTIL_UNINSTALL_METRICS_H_