Remove unused Imports and private method (flutter#15872)

Author: goderbauer

shell/platform/android/io/flutter/embedding/android/FlutterActivityAndFragmentDelegate.java

@@ -28,7 +28,6 @@
 import io.flutter.embedding.engine.dart.DartExecutor;
 import io.flutter.embedding.engine.renderer.FlutterUiDisplayListener;
 import io.flutter.plugin.platform.PlatformPlugin;
-import io.flutter.view.FlutterMain;
 
 import static android.content.ComponentCallbacks2.TRIM_MEMORY_RUNNING_LOW;
 

shell/platform/android/io/flutter/embedding/android/FlutterFragment.java

@@ -742,13 +742,6 @@ public void onLowMemory() {
     delegate.onLowMemory();
   }
 
-  @NonNull
-  private Context getContextCompat() {
-    return Build.VERSION.SDK_INT >= 23
-      ? getContext()
-      : getActivity();
-  }
-
   /**
    * {@link FlutterActivityAndFragmentDelegate.Host} method that is used by
    * {@link FlutterActivityAndFragmentDelegate} to obtain Flutter shell arguments when

shell/platform/android/io/flutter/embedding/engine/FlutterEnginePluginRegistry.java

@@ -37,7 +37,6 @@
 import io.flutter.embedding.engine.plugins.service.ServiceAware;
 import io.flutter.embedding.engine.plugins.service.ServiceControlSurface;
 import io.flutter.embedding.engine.plugins.service.ServicePluginBinding;
-import io.flutter.plugin.platform.PlatformViewsController;
 
 class FlutterEnginePluginRegistry implements PluginRegistry,
     ActivityControlSurface,