[firebase_messaging] better handling on background isolate initialization#1917

spideythewebhead wants to merge 3 commits into

firebase:masterfirebase/flutterfire:masterfrom

spideythewebhead:prevent_multiple_background_views_and_channels_creation_for_background_isolatespideythewebhead/flutterfire:prevent_multiple_background_views_and_channels_creation_for_background_isolateCopy head branch name to clipboard