Revert 170483 - Remove PrefObserver usages, batch 12.

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

Index: chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser.h
===================================================================
--- chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser.h	(revision 170518)
+++ chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser.h	(working copy)
@@ -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 "chrome/browser/extensions/extension_prefs.h"
 #include "chrome/browser/prefs/pref_service_observer.h"
 #include "chrome/browser/ui/ash/app_sync_ui_state_observer.h"
@@ -60,6 +61,7 @@
       public ash::ShellObserver,
       public ChromeLauncherController,
       public content::NotificationObserver,
+      public PrefObserver,
       public PrefServiceObserver,
       public AppSyncUIStateObserver {
  public:
@@ -235,6 +237,10 @@
                        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;