Add getter for JS Executor Factory

Reviewed By: mhorowitz

Differential Revision: D5857012

fbshipit-source-id: 8c9fc0095c512325968234f48d6728b63d61913d

ReactAndroid/src/main/java/com/facebook/react/ReactNativeHost.java

@@ -16,6 +16,7 @@
 import android.app.Application;
 
 import com.facebook.infer.annotation.Assertions;
+import com.facebook.react.bridge.JavaScriptExecutorFactory;
 import com.facebook.react.common.LifecycleState;
 import com.facebook.react.devsupport.RedBoxHandler;
 import com.facebook.react.uimanager.UIImplementationProvider;
@@ -68,6 +69,7 @@ protected ReactInstanceManager createReactInstanceManager() {
       .setJSMainModulePath(getJSMainModuleName())
       .setUseDeveloperSupport(getUseDeveloperSupport())
       .setRedBoxHandler(getRedBoxHandler())
+      .setJavaScriptExecutorFactory(getJavaScriptExecutorFactory())
       .setUIImplementationProvider(getUIImplementationProvider())
       .setInitialLifecycleState(LifecycleState.BEFORE_CREATE);
 
@@ -91,6 +93,14 @@ protected ReactInstanceManager createReactInstanceManager() {
     return null;
   }
 
+  /**
+   * Get the {@link JavaScriptExecutorFactory}.  Override this to use a custom
+   * Executor.
+   */
+  protected @Nullable JavaScriptExecutorFactory getJavaScriptExecutorFactory() {
+    return null;
+  }
+
   protected final Application getApplication() {
     return mApplication;
   }