Add onFontNameChanged event to Font Settings API

chrome/browser/extensions/extension_font_settings_api.h

Index: chrome/browser/extensions/extension_font_settings_api.h
diff --git a/chrome/browser/extensions/extension_font_settings_api.h b/chrome/browser/extensions/extension_font_settings_api.h
index 27aeb8614cbf6c5acc612f4a437d021e0a30138a..4e230e825672584abb7d3255984d8c4f19f642cc 100644
--- a/chrome/browser/extensions/extension_font_settings_api.h
+++ b/chrome/browser/extensions/extension_font_settings_api.h
@@ -7,6 +7,28 @@
 #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: