Retrieve pinned flag directly from Notification class

ui/arc/notification/arc_custom_notification_view.cc

 // 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.
 
 #include "ui/arc/notification/arc_custom_notification_view.h"
 
 #include "ash/wm/window_util.h"
 #include "base/auto_reset.h"
 #include "base/memory/ptr_util.h"
 #include "components/exo/notification_surface.h"
@@ skipping 172 matching lines @@
       return false;
     return owner_->close_button_->HasFocus();
   }
 
   void RequestFocusOnCloseButton() override {
     if (owner_->close_button_)
       owner_->close_button_->RequestFocus();
     owner_->UpdateControlButtonsVisibility();
   }
 
-  bool IsPinned() const override {
-    if (!owner_->item_)
-      return false;
-    return owner_->item_->pinned();
-  }
-
   void UpdateControlButtonsVisibility() override {
     owner_->UpdateControlButtonsVisibility();
   }
 
  private:
   ArcCustomNotificationView* const owner_;
 
   DISALLOW_COPY_AND_ASSIGN(ContentViewDelegate);
 };
 
@@ skipping 519 matching lines @@
     }
     if (close_button_) {
       close_button_->set_background(
           views::Background::CreateSolidBackground(current_color));
       close_button_->SchedulePaint();
     }
   }
 }
 
 }  // namespace arc