Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/ui/ash/launcher/chrome_launcher_controller.h

Index: chrome/browser/ui/ash/launcher/chrome_launcher_controller.h
diff --git a/chrome/browser/ui/ash/launcher/chrome_launcher_controller.h b/chrome/browser/ui/ash/launcher/chrome_launcher_controller.h
index e27982c614e0b8ed8b9a81720b31830213b04743..0c5a04b464d2dcb15f46307c759dc8d3334dd24f 100644
--- a/chrome/browser/ui/ash/launcher/chrome_launcher_controller.h
+++ b/chrome/browser/ui/ash/launcher/chrome_launcher_controller.h
@@ -18,6 +18,7 @@
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/prefs/public/pref_change_registrar.h"
+#include "base/prefs/public/pref_observer.h"
 #include "base/timer.h"
 #include "chrome/browser/api/sync/profile_sync_service_observer.h"
 #include "chrome/browser/prefs/pref_service_observer.h"
@@ -55,6 +56,7 @@ class ChromeLauncherController
       public ash::LauncherModelObserver,
       public ash::ShellObserver,
       public content::NotificationObserver,
+      public PrefObserver,
       public ProfileSyncServiceObserver,
       public PrefServiceObserver {
  public:
@@ -263,6 +265,10 @@ class ChromeLauncherController
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
+  // Overridden from PrefObserver:
+  virtual void OnPreferenceChanged(PrefServiceBase* service,
+                                   const std::string& pref_name) OVERRIDE;
+
   // Overridden from ash::ShellObserver:
   virtual void OnShelfAlignmentChanged() OVERRIDE;