Add base:: to string16 in extensions/.

extensions/browser/admin_policy.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 EXTENSIONS_BROWSER_ADMIN_POLICY_H_
 #define EXTENSIONS_BROWSER_ADMIN_POLICY_H_
 
 #include "base/values.h"
 
 namespace extensions {
 
 class Extension;
 
 // Functions for providing information about the extension whitelist,
 // blacklist, and forcelist imposed by admin policy.
 namespace admin_policy {
 
 // Checks if extensions are blacklisted by default, by policy. When true, this
 // means that even extensions without an ID should be blacklisted (e.g.
 // from the command line, or when loaded as an unpacked extension).
 bool BlacklistedByDefault(const base::ListValue* blacklist);
 
 // Returns true if the extension is allowed by the admin policy.
 bool UserMayLoad(const base::ListValue* blacklist,
                  const base::ListValue* whitelist,
                  const base::DictionaryValue* forcelist,
                  const base::ListValue* allowed_types,
                  const Extension* extension,
-                 string16* error);
+                 base::string16* error);
 
 // Returns false if the extension is required to remain running. In practice
 // this enforces the admin policy forcelist.
-bool UserMayModifySettings(const Extension* extension, string16* error);
+bool UserMayModifySettings(const Extension* extension, base::string16* error);
 
 // Returns false if the extension is required to remain running. In practice
 // this enforces the admin policy forcelist.
-bool MustRemainEnabled(const Extension* extension, string16* error);
+bool MustRemainEnabled(const Extension* extension, base::string16* error);
 
 }  // namespace
 }  // namespace
 
 #endif  // EXTENSIONS_BROWSER_ADMIN_POLICY_H_