Implement ArcNotificationDelegate::Click() for ArcCustomNotificationItem.

ui/arc/notification/arc_custom_notification_item.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_item.h"
 
 #include <memory>
 #include <string>
 #include <utility>
 
@@ skipping 21 matching lines @@
   std::unique_ptr<message_center::CustomContent> CreateCustomContent()
       override {
     auto view = base::MakeUnique<ArcCustomNotificationView>(item_);
     auto content_view_delegate = view->CreateContentViewDelegate();
     return base::MakeUnique<message_center::CustomContent>(
         std::move(view), std::move(content_view_delegate));
   }
 
   void Close(bool by_user) override { item_->Close(by_user); }
 
+  void Click() override { item_->Click(); }
+
  private:
   // The destructor is private since this class is ref-counted.
   ~ArcNotificationDelegate() override {}
 
   ArcCustomNotificationItem* const item_;
 
   DISALLOW_COPY_AND_ASSIGN(ArcNotificationDelegate);
 };
 
 }  // namespace
@@ skipping 76 matching lines @@
 }
 
 void ArcCustomNotificationItem::DecrementWindowRefCount() {
   DCHECK_GT(window_ref_count_, 0);
   --window_ref_count_;
   if (window_ref_count_ == 0)
     manager()->CloseNotificationWindow(notification_key());
 }
 
 }  // namespace arc