Add explicit base namespace to string16 users.

chrome/common/extensions/manifest_handler_helpers.h

 // 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.
 
 #ifndef CHROME_COMMON_EXTENSIONS_MANIFEST_HANDLER_HELPERS_H_
 #define CHROME_COMMON_EXTENSIONS_MANIFEST_HANDLER_HELPERS_H_
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 13 matching lines @@
 bool NormalizeAndValidatePath(std::string* path);
 
 // Loads icon paths defined in dictionary |icons_value| into ExtensionIconSet
 // |icons|. |icons_value| is a dictionary value {icon size -> icon path}. Icons
 // in |icons_value| whose size is not in |icon_sizes| will be ignored.
 // Returns success. If load fails, |error| will be set.
 bool LoadIconsFromDictionary(const base::DictionaryValue* icons_value,
                              const int* icon_sizes,
                              size_t num_icon_sizes,
                              ExtensionIconSet* icons,
-                             string16* error);
+                             base::string16* error);
 
 }  // namespace manifest_handler_helpers
 }  // namespace extensions
 
 #endif  // CHROME_COMMON_EXTENSIONS_MANIFEST_HANDLER_HELPERS_H_