Make //content responsible for generating notification Ids

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/mac/foundation_util.h"
 #include "base/mac/mac_util.h"
@@ skipping 191 matching lines @@
     NSString* toast_profile_id = [toast.userInfo
         objectForKey:notification_constants::kNotificationProfileId];
     if (toast_profile_id == current_profile_id) {
       notifications->insert(base::SysNSStringToUTF8([toast.userInfo
           objectForKey:notification_constants::kNotificationId]));
     }
   }
   return true;
 }
 
-bool NotificationPlatformBridgeMac::SupportsNotificationCenter() const {
-  return true;
-}
-
 // static
 bool NotificationPlatformBridgeMac::VerifyNotificationData(
     NSDictionary* response) {
   if (![response
           objectForKey:notification_constants::kNotificationButtonIndex] ||
       ![response objectForKey:notification_constants::kNotificationOperation] ||
       ![response objectForKey:notification_constants::kNotificationId] ||
       ![response objectForKey:notification_constants::kNotificationProfileId] ||
       ![response objectForKey:notification_constants::kNotificationIncognito] ||
       ![response objectForKey:notification_constants::kNotificationType]) {
@@ skipping 96 matching lines @@
           notificationOrigin, persistentNotificationId, buttonIndex.intValue));
 }
 
 - (BOOL)userNotificationCenter:(NSUserNotificationCenter*)center
      shouldPresentNotification:(NSUserNotification*)nsNotification {
   // Always display notifications, regardless of whether the app is foreground.
   return YES;
 }
 
 @end