Extend notifications.mojom for expandable notifications.

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 83 matching lines @@
       message_center::NOTIFICATION_TYPE_CUSTOM, notification_id(),
       base::UTF8ToUTF16(data->title), base::UTF8ToUTF16(data->message),
       gfx::Image(),
       base::UTF8ToUTF16("arc"),  // display source
       GURL(),                    // empty origin url, for system component
       notifier_id, rich_data, new ArcNotificationDelegate(this));
   notification->set_timestamp(base::Time::FromJavaTime(data->time));
   SetNotification(std::move(notification));
 
   pinned_ = rich_data.pinned;
+  expand_state_ = data->expand_state;
 
   if (!data->snapshot_image || data->snapshot_image->isNull()) {
     snapshot_ = gfx::ImageSkia();
   } else {
     snapshot_ = gfx::ImageSkia(gfx::ImageSkiaRep(
         *data->snapshot_image, data->snapshot_image_scale));
   }
 
   for (auto& observer : observers_)
     observer.OnItemUpdated();
@@ skipping 16 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