Sent when it is time to update your AppWidget.
This may be sent in response to a new instance for this AppWidget provider having been instantiated, the requested AppWidgetProviderInfo.UpdatePeriodMillis having lapsed, or the system booting.
The intent will contain the following extras:
| AppWidgetManager.ExtraAppwidgetIds | The appWidgetIds to update. This may be all of the AppWidgets created for this provider, or just a subset. The system tries to send updates for as few AppWidget instances as possible. |