Update location_background (flutter#906)

* Update location_background

packages/location_background/ios/Classes/LocationBackgroundPlugin.m

@@ -8,7 +8,7 @@
 
 @implementation LocationBackgroundPlugin {
   CLLocationManager *_locationManager;
-  FlutterHeadlessDartRunner *_headlessRunner;
+  FlutterEngine *_headlessEngine;
   FlutterMethodChannel *_callbackChannel;
   FlutterMethodChannel *_mainChannel;
   NSObject<FlutterPluginRegistrar> *_registrar;
@@ -48,7 +48,9 @@ - (BOOL)application:(UIApplication *)application
       _locationManager.showsBackgroundLocationIndicator =
           [self getShowsBackgroundLocationIndicator];
     }
-    _locationManager.allowsBackgroundLocationUpdates = YES;
+    if (@available(iOS 9.0, *)) {
+      _locationManager.allowsBackgroundLocationUpdates = YES;
+    }
     // Finally, restart monitoring for location changes to get our location.
     [self->_locationManager startMonitoringSignificantLocationChanges];
   }
@@ -97,7 +99,8 @@ - (instancetype)init:(NSObject<FlutterPluginRegistrar> *)registrar {
   [_locationManager setDelegate:self];
   [_locationManager requestAlwaysAuthorization];
 
-  _headlessRunner = [[FlutterHeadlessDartRunner alloc] init];
+  _headlessEngine =
+      [[FlutterEngine alloc] initWithName:@"io.flutter.plugins.location_background" project:nil];
   _registrar = registrar;
 
   // This is the method channel used to communicate with the UI Isolate.
@@ -113,7 +116,7 @@ - (instancetype)init:(NSObject<FlutterPluginRegistrar> *)registrar {
   // `startHeadlessService` below.
   _callbackChannel = [FlutterMethodChannel
       methodChannelWithName:@"plugins.flutter.io/ios_background_location_callback"
-            binaryMessenger:_headlessRunner];
+            binaryMessenger:_headlessEngine];
   return self;
 }
 
@@ -178,7 +181,7 @@ - (void)startHeadlessService:(int64_t)handle {
 
   // Here we actually launch the background isolate to start executing our
   // callback dispatcher, `_backgroundCallbackDispatcher`, in Dart.
-  [_headlessRunner runWithEntrypointAndLibraryUri:entrypoint libraryUri:uri];
+  [_headlessEngine runWithEntrypoint:entrypoint libraryURI:uri];
 
   // The headless runner needs to be initialized before we can register it as a
   // MethodCallDelegate or else we get an illegal memory access. If we don't
@@ -194,12 +197,14 @@ - (void)monitorLocationChanges:(NSArray *)arguments {
   _locationManager.pausesLocationUpdatesAutomatically = arguments[1];
   if (@available(iOS 11.0, *)) {
     _locationManager.showsBackgroundLocationIndicator = arguments[2];
+    [self setShowsBackgroundLocationIndicator:_locationManager.showsBackgroundLocationIndicator];
   }
   _locationManager.activityType = [arguments[3] integerValue];
-  _locationManager.allowsBackgroundLocationUpdates = YES;
+  if (@available(iOS 9.0, *)) {
+    _locationManager.allowsBackgroundLocationUpdates = YES;
+  }
 
   [self setPausesLocationUpdatesAutomatically:_locationManager.pausesLocationUpdatesAutomatically];
-  [self setShowsBackgroundLocationIndicator:_locationManager.showsBackgroundLocationIndicator];
   [self->_locationManager startMonitoringSignificantLocationChanges];
 }