Clean up Fabric startSurface API used in Venice

Summary:
Update FabricUIManager methods for `SurfaceHandler` to start usual rendering or prerendering based on presence of the view instead of using two methods with same logic.

Changelog: [Internal]

Reviewed By: sshic

Differential Revision: D30346502

fbshipit-source-id: 297f2b4a16dc7af7c36379252bd73e6dc953ff59

ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManager.java

@@ -294,14 +294,28 @@ public class FabricUIManager implements UIManager, LifecycleEventListener {
     return rootTag;
   }
 
-  public void startSurface(final SurfaceHandler surfaceHandler) {
+  public void startSurface(final SurfaceHandler surfaceHandler, final @Nullable View rootView) {
-    int rootTag = ReactRootViewTagGenerator.getNextRootViewTag();
+    final int rootTag = ReactRootViewTagGenerator.getNextRootViewTag();
-    mMountingManager.startSurface(rootTag);
 
-    startSurfaceWithId(surfaceHandler, rootTag, false);
+    if (rootView == null) {
+      mMountingManager.startSurface(rootTag);
+    } else {
+      Context context = rootView.getContext();
+      ThemedReactContext reactContext =
+          new ThemedReactContext(
+              mReactApplicationContext, context, surfaceHandler.getModuleName(), rootTag);
+      mMountingManager.startSurface(rootTag, rootView, reactContext);
     }
 
-  public void attachRootView(final View rootView, final SurfaceHandler surfaceHandler) {
+    surfaceHandler.setSurfaceId(rootTag);
+    if (surfaceHandler instanceof SurfaceHandlerBinding) {
+      mBinding.registerSurface((SurfaceHandlerBinding) surfaceHandler);
+    }
+    surfaceHandler.setMountable(rootView != null);
+    surfaceHandler.start();
+  }
+
+  public void attachRootView(final SurfaceHandler surfaceHandler, final View rootView) {
     ThemedReactContext reactContext =
         new ThemedReactContext(
             mReactApplicationContext,
@@ -313,27 +327,6 @@ public class FabricUIManager implements UIManager, LifecycleEventListener {
     surfaceHandler.setMountable(true);
   }
 
-  public void startSurfaceWithView(final View rootView, final SurfaceHandler surfaceHandler) {
-    final int rootTag = ReactRootViewTagGenerator.getNextRootViewTag();
-
-    Context context = rootView.getContext();
-    ThemedReactContext reactContext =
-        new ThemedReactContext(
-            mReactApplicationContext, context, surfaceHandler.getModuleName(), rootTag);
-    mMountingManager.startSurface(rootTag, rootView, reactContext);
-
-    startSurfaceWithId(surfaceHandler, rootTag, true);
-  }
-
-  private void startSurfaceWithId(SurfaceHandler surfaceHandler, int rootTag, boolean isMountable) {
-    surfaceHandler.setSurfaceId(rootTag);
-    if (surfaceHandler instanceof SurfaceHandlerBinding) {
-      mBinding.registerSurface((SurfaceHandlerBinding) surfaceHandler);
-    }
-    surfaceHandler.setMountable(isMountable);
-    surfaceHandler.start();
-  }
-
   public void stopSurface(final SurfaceHandler surfaceHandler) {
     if (!surfaceHandler.isRunning()) {
       ReactSoftExceptionLogger.logSoftException(