Retrive displayed notifications asynchronously

chrome/browser/notifications/notification_common.h

Index: chrome/browser/notifications/notification_common.h
diff --git a/chrome/browser/notifications/notification_common.h b/chrome/browser/notifications/notification_common.h
index 280c84df461e0fe43a28fa0c4751d4f758392a2b..6b8d0b6be1b61f31c33422de92b0666953926bb7 100644
--- a/chrome/browser/notifications/notification_common.h
+++ b/chrome/browser/notifications/notification_common.h
@@ -5,6 +5,11 @@
 #ifndef CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_COMMON_H_
 #define CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_COMMON_H_
 
+#include <set>
+#include <string>
+
+#include "base/callback.h"
+
 namespace content {
 class BrowserContext;
 }  // namespace content
@@ -12,6 +17,10 @@ class BrowserContext;
 // Shared functionality for both in page and persistent notification
 class NotificationCommon {
  public:
+  using NotificationResultCallback =
+      base::Callback<void(std::unique_ptr<std::set<std::string>>,
+                          bool /* success */)>;
+
   // Things as user can do to a notification.
   enum Operation {
     CLICK = 0,