Add base:: to string16 in extensions/.

extensions/common/permissions/api_permission_set.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_COMMON_PERMISSIONS_API_PERMISSION_SET_H_
 #define EXTENSIONS_COMMON_PERMISSIONS_API_PERMISSION_SET_H_
 
 
 #include "extensions/common/permissions/api_permission.h"
 #include "extensions/common/permissions/base_set_operators.h"
@@ skipping 36 matching lines @@
   // permissions with kFlagInternal as errors. If |unhandled_permissions| is
   // not NULL, the names of all permissions that couldn't be parsed will be
   // added to this vector. If |error| is NULL, parsing will continue with the
   // next permission if invalid data is detected. If |error| is not NULL, it
   // will be set to an error message and false is returned when an invalid
   // permission is found.
   static bool ParseFromJSON(
       const base::ListValue* permissions,
       ParseSource source,
       APIPermissionSet* api_permissions,
-      string16* error,
+      base::string16* error,
       std::vector<std::string>* unhandled_permissions);
 
   void AddImpliedPermissions();
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_PERMISSIONS_API_PERMISSION_SET_H_