Add onFontNameChanged event to Font Settings API

chrome/browser/extensions/extension_font_settings_api.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_BROWSER_EXTENSIONS_EXTENSION_FONT_SETTINGS_API_H__
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_FONT_SETTINGS_API_H__
 #pragma once
 
 #include "chrome/browser/extensions/extension_function.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
+
+class ExtensionFontSettingsEventRouter : public content::NotificationObserver {
+ public:
+  explicit ExtensionFontSettingsEventRouter(Profile* profile);
+  virtual ~ExtensionFontSettingsEventRouter();
+
+  void Init();
+
+ private:
+  // content::NotificationObserver implementation.
+  virtual void Observe(int type,
+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) OVERRIDE;
+
+  PrefChangeRegistrar registrar_;
+
+  // Weak, owns us (transitively via ExtensionService).
+  Profile* profile_;
+
+  DISALLOW_COPY_AND_ASSIGN(ExtensionFontSettingsEventRouter);
+};
 
 class GetFontNameFunction : public SyncExtensionFunction {
  public:
   virtual bool RunImpl() OVERRIDE;
   DECLARE_EXTENSION_FUNCTION_NAME("experimental.fontSettings.getFontName")
 };
 
 class SetFontNameFunction : public SyncExtensionFunction {
  public:
   virtual bool RunImpl() OVERRIDE;
@@ skipping 76 matching lines @@
 class SetMinimumFontSizeFunction : public SetFontSizeExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION_NAME(
       "experimental.fontSettings.setMinimumFontSize")
 
  protected:
   virtual const char* GetPrefName() OVERRIDE;
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_FONT_SETTINGS_API_H__