[lazerg]

Summary:

With view recycling on, a view can sit in the pool while it still has a parent. If that parent called startViewTransition on it and then left the window before endViewTransition, the parent drops the view from its disappearing children but keeps itself as view.getParent(). The existing removeView call in createViewInstance can't clear that, so the recycled view goes back to the mounting layer and addViewAt crashes with "The specified child already has a parent". react-native-screens hits this when it pops a screen.

Now createViewInstance only reuses a pooled view if its parent is gone after the removeView call, and creates a new view otherwise. Views pooled while still attached to a non-recycling parent are reused as before.

Fixes #59863

Changelog:

[ANDROID] [FIXED] - Fix "The specified child already has a parent" crash when a recycled view is still held by a parent's view transition

Test Plan:

Added testViewStillHeldByADetachedParentIsNotRecycled to BaseViewManagerTest. It holds a view with startViewTransition, removes it, detaches the parent from the window, drops the view, and adds the next created view to a new parent. Without the fix it throws IllegalStateException: The specified child already has a parent; with the fix it passes.

./gradlew :packages:react-native:ReactAndroid:testDebugUnitTest

The full ReactAndroid unit test suite passes. format-check-java and format-check-kotlin are clean. I didn't run the reproducer app on a device.