Note that the FCM JavaScript SDK supports only display notifications and does not have upstream messaging capabilities. If you rely on these features, keep an eye on the chrome.gcm API migration bug.
Adopt the FCM client SDK by following the getting started guide. Some chrome.gcm functions are similar to firebase.messaging functions, such as chrome.gcm.onMessage and firebase.messaging().onMessage. Others, such as chrome.gcm.onMessagesDeleted, chrome.gcm.send, and chrome.gcm.onSendError, are not supported by the FCM client SDK.
Unevaluated requests
- Web Push API requires a notification to be shown
- Web Push API does not support an upstream channel (chrome.gcm.send())