Allow resolving view from FabricUIManager

Summary: Changelog: [Internal]

Reviewed By: JoshuaGross

Differential Revision: D30043188

fbshipit-source-id: d8675754b29fb58a28a06777f602098da6dbc27f

ReactAndroid/src/main/java/com/facebook/react/bridge/UIManager.java

@@ -117,6 +117,16 @@ public interface UIManager extends JSIModule, PerformanceCounter {
    */
   void removeUIManagerEventListener(UIManagerListener listener);
 
+  /**
+   * Resolves a view based on its reactTag. Do not mutate properties on this view that are already
+   * managed by React, as there are no guarantees this changes will be preserved.
+   *
+   * @throws IllegalViewOperationException if tag could not be resolved.
+   * @param reactTag tag
+   * @return view if found
+   */
+  View resolveView(int reactTag);
+
   /**
    * This method dispatches events from RN Android code to JS. The delivery of this event will not
    * be queued in EventDispatcher class.

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

@@ -804,6 +804,14 @@ public class FabricUIManager implements UIManager, LifecycleEventListener {
         doLeftAndRightSwapInRTL);
   }
 
+  @Override
+  public View resolveView(int reactTag) {
+    UiThreadUtil.assertOnUiThread();
+
+    SurfaceMountingManager surfaceManager = mMountingManager.getSurfaceManagerForView(reactTag);
+    return surfaceManager == null ? null : surfaceManager.getView(reactTag);
+  }
+
   @Override
   public void receiveEvent(int reactTag, String eventName, @Nullable WritableMap params) {
     receiveEvent(View.NO_ID, reactTag, eventName, params);

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

@@ -928,8 +928,18 @@ public class SurfaceMountingManager {
     return viewState == null ? null : viewState.mEventEmitter;
   }
 
-  @NonNull
-  private ViewState getViewState(int tag) {
+  @UiThread
+  public View getView(int reactTag) {
+    ViewState state = getNullableViewState(reactTag);
+    View view = state == null ? null : state.mView;
+    if (view == null) {
+      throw new IllegalViewOperationException(
+          "Trying to resolve view with tag " + reactTag + " which doesn't exist");
+    }
+    return view;
+  }
+
+  private @NonNull ViewState getViewState(int tag) {
     ViewState viewState = mTagToViewState.get(tag);
     if (viewState == null) {
       throw new RetryableMountingLayerException("Unable to find viewState for tag " + tag);

ReactAndroid/src/main/java/com/facebook/react/uimanager/UIManagerModule.java

@@ -955,6 +955,7 @@ public class UIManagerModule extends ReactContextBaseJavaModule
     public void onLowMemory() {}
   }
 
+  @Override
   public View resolveView(int tag) {
     UiThreadUtil.assertOnUiThread();
     return mUIImplementation