unregisterContentObserver method
Implementation
void unregisterContentObserver(ContentObserverCallback callback) {
String? uri;
_contentObserverCallbacks.entries.forEach((entry) {
var list = entry.value;
if (list.contains(callback) && list.length == 1) {
uri = entry.key;
}
_contentObserverCallbacks[entry.key]!
.removeWhere((element) => element == callback);
});
if (uri != null) {
invokeMethod(_UNREGISTER_CONTENT_OBSERVER, {"uri": uri});
}
}