[Mac] Add XPC alerts to GetDisplayedNotifications

content/public/browser/platform_notification_service.h

Index: content/public/browser/platform_notification_service.h
diff --git a/content/public/browser/platform_notification_service.h b/content/public/browser/platform_notification_service.h
index c1ad9ecd12d03f138b9723274bd68626e4583cad..655d05ddb3e9bd96e5b083840e28e388cf6e74a3 100644
--- a/content/public/browser/platform_notification_service.h
+++ b/content/public/browser/platform_notification_service.h
@@ -84,6 +84,13 @@ class CONTENT_EXPORT PlatformNotificationService {
   virtual bool GetDisplayedNotifications(
       BrowserContext* browser_context,
       std::set<std::string>* displayed_notifications) = 0;
+
+  // Asynchronous version of |GetDisplayedNotifications|
+  // TODO(miguelg) remove the sync version once all paths are ported.
+  virtual void GetDisplayedNotificationsAsync(
+      BrowserContext* browser_context,
+      const base::Callback<void(std::unique_ptr<std::set<std::string>>,
+                                bool /* support sync */)>&) = 0;

[Peter Beverloo, 2017/02/24 16:12:24]

Please define the callback's type with a `using` at the top of this class.

support sync -> whatever you end up with per the other comment

 };
 
 }  // namespace content