java.lang.NullPointerException: after deploying Picture in Picture sample on devices

##### Steps
1) Open Picture in Picture sample In Electric Eel Patch 2 build or Flamingo RC builds
2) Update gradle and AGP versions
3) Try to deploy on the device (I used API 30 Pixel 3 XL)

##### Actual :
I see below exception in Logcat after deployment
```
023-03-23 12:13:40.932 28748-28748 AndroidRuntime com...mple.android.pictureinpicture E FATAL EXCEPTION: main
Process: com.example.android.pictureinpicture, PID: 28748
java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.core.view.WindowInsetsControllerCompat.show(int)' on a null object reference
at com.example.android.pictureinpicture.MainActivity.adjustFullScreen(MainActivity.java:313)
at com.example.android.pictureinpicture.MainActivity.onWindowFocusChanged(MainActivity.java:241)
at androidx.appcompat.view.WindowCallbackWrapper.onWindowFocusChanged(WindowCallbackWrapper.java:124)
at com.android.internal.policy.DecorView.onWindowFocusChanged(DecorView.java:1692)
at android.view.View.dispatchWindowFocusChanged(View.java:13703)
at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:1480)
at android.view.ViewRootImpl.handleWindowFocusChanged(ViewRootImpl.java:2870)
at android.view.ViewRootImpl.access$1100(ViewRootImpl.java:142)
at android.view.ViewRootImpl$ViewRootHandler.handleMessage(ViewRootImpl.java:4533)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7356)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
2023-03-23 12:13:40.949 28748-28748 Process com...mple.android.pictureinpicture I Sending signal. PID: 28748 SIG: 9
2023-03-23 12:13:40.961 1388-1703 InputDispatcher system_process E channel '264e43a com.example.android.pictureinpicture/com.example.android.pictureinpicture.MainActivity (server)' ~ Channel is unrecoverably broken and will be disposed!

Start in MainActivity.java at adjustFullScreen (line 313) and trace its call from onWindowFocusChanged (line 241). Reproduce the Picture in Picture sample on an API 30 Pixel 3 XL after updating Gradle and AGP, then verify deployment no longer produces the reported NullPointerException in Logcat.

Written by the indexing model from the issue text.