change(android): make FabricUIManager#resolveView not thread specific

[hannojg]

Summary:

FabricUIManager#resolveView is not using any thread specific annotation, but has a UiThreadUtil.assertOnUiThread() check:

https://github.com/facebook/react-native/blob/d9262c60f4c02d66417008970dc9c34b742aaa75/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManager.java#L1034-L1037

However, after checking all data structures used, it appears that all of them are ConcurrentHashMaps and thus FabricUIManager#resolveView is actually thread safe:

https://github.com/facebook/react-native/blob/d93d32547bfadba731999ea251ca5e1d6c6c8912/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManager.java#L1038

https://github.com/facebook/react-native/blob/d93d32547bfadba731999ea251ca5e1d6c6c8912/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/mounting/SurfaceMountingManager.java#L81

https://github.com/facebook/react-native/blob/d93d32547bfadba731999ea251ca5e1d6c6c8912/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/mounting/MountingManager.kt#L43

I am proposing to remove the UiThreadUtil.assertOnUiThread() check here.

Motivation:

From another thread we want to check if a certain react tag is already mounted in the native view hierarchy. It should be the callers responsibility to make sure to only operate on that view from the UI thread.

Changelog:

[ANDROID] [CHANGED] Make FabricUIManager#resolveView not thread specific

Test Plan:

• Run the example app and make sure everything still works
• We tested this change and calling this method from another thread and it works without any weirdnesses

[react-native-bot]

This PR is stale because it has been open for 180 days with no activity. It will be closed in 7 days unless you comment on it or remove the "Stale" label.

[hannojg]

still interested in this