[Deprecated in Chrome 44, removed in Chrome 45] The Push API previously exposed two properties identifying the subscription: {endpoint, subscriptionId}. These will be merged to be only a single property: endpoint. Developers can update their implementation by only considering endpoint if it considers the contents of subscriptionId.
Docs: https://developer.mozilla.org/en-US/docs/Web/API/PushSubscription/subscriptionId https://developer.mozilla.org/en-US/docs/Web/API/PushSubscription/endpoint http://updates.html5rocks.com/2015/05/Notifying-you-of-notificiation-changes
Samples: https://github.com/GoogleChrome/samples/tree/gh-pages/push-messaging-and-notifications