Try to call setSurfaceId and setId earlier on ReactRootViews

Summary:
We assume that startSurface is always called off the UI thread; see if we can synchronously call setId and setSurfaceId, and in general, call setSurfaceId sooner.

Changelog: [Internal]

Reviewed By: mdvacca

Differential Revision: D26053050

fbshipit-source-id: a657584502bb0018e9591fe610eac0fc9fab2ca9

ReactAndroid/src/main/java/com/facebook/react/fabric/mounting/SurfaceMountingManager.java

@@ -29,6 +29,7 @@
 import com.facebook.react.fabric.events.EventEmitterWrapper;
 import com.facebook.react.touch.JSResponderHandler;
 import com.facebook.react.uimanager.IllegalViewOperationException;
+import com.facebook.react.uimanager.ReactRoot;
 import com.facebook.react.uimanager.ReactStylesDiffMap;
 import com.facebook.react.uimanager.RootView;
 import com.facebook.react.uimanager.RootViewManager;
@@ -136,7 +137,7 @@ private void addRootView(@NonNull final View rootView) {
     // Since this is called from the constructor, we know the surface cannot have stopped yet.
     mTagToViewState.put(mSurfaceId, new ViewState(mSurfaceId, rootView, mRootViewManager, true));
 
-    UiThreadUtil.runOnUiThread(
+    Runnable runnable =
         new Runnable() {
           @Override
           public void run() {
@@ -158,8 +159,18 @@ public void run() {
                       + "explicitly overwrite the id field to View.NO_ID before calling addRootView.");
             }
             rootView.setId(mSurfaceId);
+
+            if (rootView instanceof ReactRoot) {
+              ((ReactRoot) rootView).setRootViewTag(mSurfaceId);
+            }
           }
-        });
+        };
+
+    if (UiThreadUtil.isOnUiThread()) {
+      runnable.run();
+    } else {
+      UiThreadUtil.runOnUiThread(runnable);
+    }
   }
 
   /**