Docs: Need to mention messaging-sender-id in firebase-messaging

[robdodson]

Quick note:

If you're using firebase-messaging along with firebase-app, you need to add messaging-sender-id to firebase-app. Otherwise it will call initializeApp without it, and when firebase-messaging boots up it will trigger an error

[andrewillard]

Hi @robdodson, There is a plan to create a custom element for firebase-messaging ?

Thanks.

[robdodson]

@andrew-silva-movile there already is one, it's in this repo. You can find the docs here: https://beta.webcomponents.org/element/firebase/polymerfire/firebase-messaging

[andrewillard]

thanks @robdodson, I just watched your last polycast about it, it was amazing as always! I need to stop searching in Polymer Catalog and start searching in webcomponents.org.