Make GetDisplayedNotifications asynchronous.

chrome/browser/notifications/notification_platform_bridge_mac.mm

 // 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.
 
 #include "chrome/browser/notifications/notification_platform_bridge_mac.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 255 matching lines @@
 #if BUILDFLAG(ENABLE_XPC_NOTIFICATIONS)
   // If no banner existed with that ID try to see if there is an alert
   // in the xpc server.
   if (!notification_removed) {
     [alert_dispatcher_ closeNotificationWithId:candidate_id
                                  withProfileId:current_profile_id];
   }
 #endif  // ENABLE_XPC_NOTIFICATIONS
 }
 
-bool NotificationPlatformBridgeMac::GetDisplayed(
+void NotificationPlatformBridgeMac::GetDisplayed(
     const std::string& profile_id,
     bool incognito,
-    std::set<std::string>* notifications) const {
-  DCHECK(notifications);
-
+    const DisplayedNotificationsCallback& callback) const {
+  auto displayed_notifications = base::MakeUnique<std::set<std::string>>();
   NSString* current_profile_id = base::SysUTF8ToNSString(profile_id);
   for (NSUserNotification* toast in
        [notification_center_ deliveredNotifications]) {
     NSString* toast_profile_id = [toast.userInfo
         objectForKey:notification_constants::kNotificationProfileId];
     if ([toast_profile_id isEqualToString:current_profile_id]) {
-      notifications->insert(base::SysNSStringToUTF8([toast.userInfo
+      displayed_notifications->insert(base::SysNSStringToUTF8([toast.userInfo
           objectForKey:notification_constants::kNotificationId]));
     }
   }
-  return true;
+  content::BrowserThread::PostTask(
+      content::BrowserThread::UI, FROM_HERE,
+      base::Bind(callback, base::Passed(&displayed_notifications),
+                 true /* supports sync */));
 }
 
 // static
 void NotificationPlatformBridgeMac::ProcessNotificationResponse(
     NSDictionary* response) {
   if (!NotificationPlatformBridgeMac::VerifyNotificationData(response))
     return;
 
   NSNumber* button_index =
       [response objectForKey:notification_constants::kNotificationButtonIndex];
@@ skipping 174 matching lines @@
   [[xpcConnection_ remoteObjectProxy] closeAllNotifications];
 }
 
 // NotificationReply implementation
 - (void)notificationClick:(NSDictionary*)notificationResponseData {
   NotificationPlatformBridgeMac::ProcessNotificationResponse(
       notificationResponseData);
 }
 
 @end