chromeos: Show deprecated accelerator notifications in mash

ash/accelerators/accelerator_controller_delegate_aura.h

Index: ash/accelerators/accelerator_controller_delegate_aura.h
diff --git a/ash/accelerators/accelerator_controller_delegate_aura.h b/ash/accelerators/accelerator_controller_delegate_aura.h
index 3f683820f7d90c489a17998c583ebe5a6a480bbb..549dd71346d783a549e7ef77a8acec35b1dab6d3 100644
--- a/ash/accelerators/accelerator_controller_delegate_aura.h
+++ b/ash/accelerators/accelerator_controller_delegate_aura.h
@@ -36,10 +36,6 @@ class ASH_EXPORT AcceleratorControllerDelegateAura
                         const ui::Accelerator& previous_accelerator) override;
   void PerformAction(AcceleratorAction action,
                      const ui::Accelerator& accelerator) override;
-  void ShowDeprecatedAcceleratorNotification(const char* const notification_id,
-                                             int message_id,
-                                             int old_shortcut_id,
-                                             int new_shortcut_id) override;
 
  private:
   std::unique_ptr<ScreenshotDelegate> screenshot_delegate_;