Hide the settings button on a notification in MNC.

ui/arc/notification/arc_custom_notification_view.h

 // Copyright 2016 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 UI_ARC_NOTIFICATION_ARC_CUSTOM_NOTIFICATION_VIEW_H_
 #define UI_ARC_NOTIFICATION_ARC_CUSTOM_NOTIFICATION_VIEW_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 45 matching lines @@
     void OnFocus() override;
     void OnBlur() override;
 
    private:
     ArcCustomNotificationView* const owner_;
 
     DISALLOW_COPY_AND_ASSIGN(ControlButton);
   };
 
   void CreateCloseButton();
+  void CreateSettingsButton();
   void CreateFloatingControlButtons();
   void SetSurface(exo::NotificationSurface* surface);
   void UpdatePreferredSize();
   void UpdateControlButtonsVisibility();
   void UpdatePinnedState();
   void UpdateSnapshot();
   void AttachSurface();
   void ActivateToast();
 
   // views::NativeViewHost
@@ skipping 54 matching lines @@
 
   // Protects from call loops between Layout and OnWindowBoundsChanged.
   bool in_layout_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(ArcCustomNotificationView);
 };
 
 }  // namespace arc
 
 #endif  // UI_ARC_NOTIFICATION_ARC_CUSTOM_NOTIFICATION_VIEW_H_