Add base:: to string16 in extensions/.

extensions/common/permissions/manifest_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_MANIFEST_PERMISSION_SET_H_
 #define EXTENSIONS_COMMON_PERMISSIONS_MANIFEST_PERMISSION_SET_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 20 matching lines @@
  public:
   // Parses permissions from |permissions| and adds the parsed permissions to
   // |manifest_permissions|. 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,
       ManifestPermissionSet* manifest_permissions,
-      string16* error,
+      base::string16* error,
       std::vector<std::string>* unhandled_permissions);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_PERMISSIONS_MANIFEST_PERMISSION_SET_H_