Listening for `ACTION_MY_PACKAGE_REPLACED` [1] is the easiest way to get
notified when the app has been updated.
This broadcast, while not explicitly exempt from Oreo's Background Execution
Limits [2] is considered explicit because it is sent only to the package being
replaced and so it is compatible with the new limitations.
The previous intent action was chosen because at that time this action was not
supported by all platforms Fennec ran on [3], but this is not the case anymore.
The other broadcast - `ACTION_NOTIFICATION_CANCELLED` that this receiver
listens to is send explicitly.
[1] https://developer.android.com/reference/android/content/Intent.html#ACTION_MY_PACKAGE_REPLACED
[2] https://developer.android.com/guide/components/broadcast-exceptions
[3] 5c06063be6
MozReview-Commit-ID: DLUdw906i3P
--HG--
extra : rebase_source : a8544ae169344896aba4c7b922b68af4ad4bc94c
extra : histedit_source : c41c60cedea452ba8662fa836faa2aa8f9b5627e