Make GetDisplayedNotifications asynchronous.

chrome/browser/notifications/platform_notification_service_impl.h

 // Copyright 2014 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.
 
 #ifndef CHROME_BROWSER_NOTIFICATIONS_PLATFORM_NOTIFICATION_SERVICE_IMPL_H_
 #define CHROME_BROWSER_NOTIFICATIONS_PLATFORM_NOTIFICATION_SERVICE_IMPL_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 77 matching lines @@
       base::Closure* cancel_callback) override;
   void DisplayPersistentNotification(
       content::BrowserContext* browser_context,
       const std::string& notification_id,
       const GURL& service_worker_scope,
       const GURL& origin,
       const content::PlatformNotificationData& notification_data,
       const content::NotificationResources& notification_resources) override;
   void ClosePersistentNotification(content::BrowserContext* browser_context,
                                    const std::string& notification_id) override;
-  bool GetDisplayedNotifications(
+  void GetDisplayedNotifications(
       content::BrowserContext* browser_context,
-      std::set<std::string>* displayed_notifications) override;
+      const DisplayedNotificationsCallback& callback) override;
 
  private:
   friend struct base::DefaultSingletonTraits<PlatformNotificationServiceImpl>;
   friend class PlatformNotificationServiceBrowserTest;
   friend class PlatformNotificationServiceTest;
   friend class PushMessagingBrowserTest;
   FRIEND_TEST_ALL_PREFIXES(PlatformNotificationServiceTest,
                            CreateNotificationFromData);
   FRIEND_TEST_ALL_PREFIXES(PlatformNotificationServiceTest,
                            DisplayNameForContextMessage);
@@ skipping 47 matching lines @@
   // programmatically to avoid dispatching close events for them.
   std::unordered_set<std::string> closed_notifications_;
 
   // Only set and used for tests, owned by the caller in that case.
   NotificationDisplayService* test_display_service_;
 
   DISALLOW_COPY_AND_ASSIGN(PlatformNotificationServiceImpl);
 };
 
 #endif  // CHROME_BROWSER_NOTIFICATIONS_PLATFORM_NOTIFICATION_SERVICE_IMPL_H_