Make GetDisplayedNotifications asynchronous.

chrome/browser/notifications/notification_platform_bridge_mac.h

 // Copyright 2015 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_NOTIFICATION_PLATFORM_BRIDGE_MAC_H_
 #define CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_PLATFORM_BRIDGE_MAC_H_
 
 #include <set>
 #include <string>
 
@@ skipping 21 matching lines @@
 
   // NotificationPlatformBridge implementation.
   void Display(NotificationCommon::Type notification_type,
                const std::string& notification_id,
                const std::string& profile_id,
                bool incognito,
                const Notification& notification) override;
 
   void Close(const std::string& profile_id,
              const std::string& notification_id) override;
-  bool GetDisplayed(const std::string& profile_id,
-                    bool incognito,
-                    std::set<std::string>* notifications) const override;
+  void GetDisplayed(
+      const std::string& profile_id,
+      bool incognito,
+      const DisplayedNotificationsCallback& callback) const override;
 
   // Processes a notification response generated from a user action
   // (click close, etc.).
   static void ProcessNotificationResponse(NSDictionary* response);
 
   // Validates contents of the |response| dictionary as received from the system
   // when a notification gets activated.
   static bool VerifyNotificationData(NSDictionary* response) WARN_UNUSED_RESULT;
 
  private:
   // Cocoa class that receives callbacks from the NSUserNotificationCenter.
   base::scoped_nsobject<NotificationCenterDelegate> delegate_;
 
   // The notification center to use for local banner notifications,
   // this can be overriden in tests.
   base::scoped_nsobject<NSUserNotificationCenter> notification_center_;
 
   // The object in charge of dispatching remote notifications.
   base::scoped_nsprotocol<id<AlertDispatcher>> alert_dispatcher_;
 
   DISALLOW_COPY_AND_ASSIGN(NotificationPlatformBridgeMac);
 };
 
 #endif  // CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_PLATFORM_BRIDGE_MAC_H_