[video_player]Fixes Playing video from asset on Android (flutter#3123)

Author: ponnamkarthik

packages/video_player/video_player/android/src/main/java/io/flutter/plugins/videoplayer/VideoPlayerPlugin.java

@@ -8,7 +8,7 @@
 import android.os.Build;
 import android.util.Log;
 import android.util.LongSparseArray;
-import io.flutter.embedding.engine.loader.FlutterLoader;
+import io.flutter.FlutterInjector;
 import io.flutter.embedding.engine.plugins.FlutterPlugin;
 import io.flutter.plugin.common.BinaryMessenger;
 import io.flutter.plugin.common.EventChannel;
@@ -60,6 +60,7 @@ public static void registerWith(io.flutter.plugin.common.PluginRegistry.Registra
 
   @Override
   public void onAttachedToEngine(FlutterPluginBinding binding) {
+
     if (android.os.Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
       try {
         HttpsURLConnection.setDefaultSSLSocketFactory(new CustomSSLSocketFactory());
@@ -73,14 +74,13 @@ public void onAttachedToEngine(FlutterPluginBinding binding) {
       }
     }
 
-    @SuppressWarnings("deprecation")
-    final FlutterLoader flutterLoader = FlutterLoader.getInstance();
+    final FlutterInjector injector = FlutterInjector.instance();
     this.flutterState =
         new FlutterState(
             binding.getApplicationContext(),
             binding.getBinaryMessenger(),
-            flutterLoader::getLookupKeyForAsset,
-            flutterLoader::getLookupKeyForAsset,
+            injector.flutterLoader()::getLookupKeyForAsset,
+            injector.flutterLoader()::getLookupKeyForAsset,
             binding.getTextureRegistry());
     flutterState.startListening(this, binding.getBinaryMessenger());
   }