Revert changes to have ExtensionService notify ThemeService directly

chrome/browser/themes/theme_service_factory.h

Index: chrome/browser/themes/theme_service_factory.h
diff --git a/chrome/browser/themes/theme_service_factory.h b/chrome/browser/themes/theme_service_factory.h
index f74f167ff2a0fe4869e3054c1bb63fb5b5002306..be7b956843ac4ebbd01416e7ca9ce9efd1400c98 100644
--- a/chrome/browser/themes/theme_service_factory.h
+++ b/chrome/browser/themes/theme_service_factory.h
@@ -26,15 +26,10 @@ class ThemeServiceFactory : public ProfileKeyedServiceFactory {
   // still needs a ThemeService to hand back the default theme images.
   static ThemeService* GetForProfile(Profile* profile);
 
-  // If the theme service for |profile| has been instantiated,
-  // immediately sets its theme to |theme|.  Otherwise, saves
-  // |theme|'s ID so that the theme service picks it up when it gets
-  // initialized.
-  //
-  // |theme| must already be installed in the extension service.
-  static void SetThemeForProfile(
-      Profile* profile,
-      const extensions::Extension* theme);
+  // Returns the Extension that implements the theme associated with
+  // |profile|. Returns NULL if the theme is no longer installed, if there is
+  // no installed theme, or the theme was cleared.
+  static const extensions::Extension* GetThemeForProfile(Profile* profile);
 
   static ThemeServiceFactory* GetInstance();