Add onFontNameChanged event to Font Settings API

chrome/browser/extensions/extension_preference_helpers.h

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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_BROWSER_EXTENSIONS_EXTENSION_PREFERENCE_HELPERS_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_PREFERENCE_HELPERS_H_
 #pragma once
 
 #include <string>
 
 #include "chrome/browser/extensions/extension_prefs_scope.h"
 
+class Profile;
+
 namespace extension_preference_helpers {
 bool StringToScope(const std::string& s, ExtensionPrefsScope* scope);
+
+// Returns a string constant (defined in the API) indicating the level of
+// control this extension has over the specified preference.
+const char* GetLevelOfControl(
+    Profile* profile,
+    const std::string& extension_id,
+    const std::string& browser_pref,
+    bool incognito);
 }
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_PREFERENCE_HELPERS_H_