Revert changes to have ExtensionService notify ThemeService directly

chrome/browser/themes/theme_service_factory.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_THEMES_THEME_SERVICE_FACTORY_H_
 #define CHROME_BROWSER_THEMES_THEME_SERVICE_FACTORY_H_
 
 #include "base/basictypes.h"
 #include "base/memory/singleton.h"
 #include "chrome/browser/profiles/profile_keyed_service_factory.h"
 
 class Profile;
 class ThemeService;
 
 namespace extensions {
 class Extension;
 }
 
 // Singleton that owns all ThemeServices and associates them with
 // Profiles. Listens for the Profile's destruction notification and cleans up
 // the associated ThemeService.
 class ThemeServiceFactory : public ProfileKeyedServiceFactory {
  public:
   // Returns the ThemeService that provides theming resources for
   // |profile|. Note that even if a Profile doesn't have a theme installed, it
   // 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();
 
  private:
   friend struct DefaultSingletonTraits<ThemeServiceFactory>;
 
   ThemeServiceFactory();
   virtual ~ThemeServiceFactory();
 
   // ProfileKeyedServiceFactory:
   virtual ProfileKeyedService* BuildServiceInstanceFor(
       Profile* profile) const OVERRIDE;
   virtual void RegisterUserPrefs(PrefService* prefs) OVERRIDE;
   virtual bool ServiceRedirectedInIncognito() const OVERRIDE;
 
   DISALLOW_COPY_AND_ASSIGN(ThemeServiceFactory);
 };
 
 #endif  // CHROME_BROWSER_THEMES_THEME_SERVICE_FACTORY_H_