Implement getting notifications up to the browser process.

content/browser/notifications/notification_message_filter.cc

Index: content/browser/notifications/notification_message_filter.cc
diff --git a/content/browser/notifications/notification_message_filter.cc b/content/browser/notifications/notification_message_filter.cc
index a4a91f409b4c87cb83724f2ed9fff0fcc34eff17..d6633ae9213960e5d4cbbef82bab5148e26d4bc7 100644
--- a/content/browser/notifications/notification_message_filter.cc
+++ b/content/browser/notifications/notification_message_filter.cc
@@ -43,6 +43,8 @@ bool NotificationMessageFilter::OnMessageReceived(const IPC::Message& message) {
                         OnShowPlatformNotification)
     IPC_MESSAGE_HANDLER(PlatformNotificationHostMsg_ShowPersistent,
                         OnShowPersistentNotification)
+    IPC_MESSAGE_HANDLER(PlatformNotificationHostMsg_GetNotifications,
+                        OnGetNotifications)
     IPC_MESSAGE_HANDLER(PlatformNotificationHostMsg_Close,
                         OnClosePlatformNotification)
     IPC_MESSAGE_HANDLER(PlatformNotificationHostMsg_ClosePersistent,
@@ -122,6 +124,22 @@ void NotificationMessageFilter::OnShowPersistentNotification(
                                          icon, notification_data);
 }
 
+void NotificationMessageFilter::OnGetNotifications(
+    int request_id,
+    int64_t service_worker_registration_id,
+    const GURL& origin,
+    const std::string& filter_tag) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  // TODO(peter): Implement retrieval of persistent Web Notifications from the
+  // database. Reply with an empty vector until this has been implemented.
+  // Tracked in https://crbug.com/442143.
+
+  Send(new PlatformNotificationMsg_DidGetNotifications(
+      request_id,
+      std::vector<PersistentNotificationInfo>()));
+}
+
 void NotificationMessageFilter::OnClosePlatformNotification(
     int notification_id) {
   if (!close_closures_.count(notification_id))