Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/profiles/gaia_info_update_service.h

Index: chrome/browser/profiles/gaia_info_update_service.h
diff --git a/chrome/browser/profiles/gaia_info_update_service.h b/chrome/browser/profiles/gaia_info_update_service.h
index 712932836c9ed2531d5580d1fbb0b1acb19c2e3d..bd4ca60e245cf482f3956137b2317f406586d054 100644
--- a/chrome/browser/profiles/gaia_info_update_service.h
+++ b/chrome/browser/profiles/gaia_info_update_service.h
@@ -8,11 +8,11 @@
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/prefs/public/pref_observer.h"
 #include "base/timer.h"
 #include "chrome/browser/api/prefs/pref_member.h"
 #include "chrome/browser/profiles/profile_downloader.h"
 #include "chrome/browser/profiles/profile_downloader_delegate.h"
-#include "content/public/browser/notification_observer.h"
 
 class Profile;
 class ProfileDownloader;
@@ -20,7 +20,7 @@ class ProfileDownloader;
 // This service kicks off a download of the user's name and profile picture.
 // The results are saved in the profile info cache.
 class GAIAInfoUpdateService : public ProfileDownloaderDelegate,
-                              public content::NotificationObserver {
+                              public PrefObserver {
  public:
   explicit GAIAInfoUpdateService(Profile* profile);
   virtual ~GAIAInfoUpdateService();
@@ -45,10 +45,9 @@ class GAIAInfoUpdateService : public ProfileDownloaderDelegate,
  private:
   FRIEND_TEST_ALL_PREFIXES(GAIAInfoUpdateServiceTest, ScheduleUpdate);
 
-  // content::NotificationObserver:
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) OVERRIDE;
+  // PrefObserver:
+  virtual void OnPreferenceChanged(PrefServiceBase* service,
+                                   const std::string& pref_name) OVERRIDE;
 
 
   void OnUsernameChanged();