Occasionally (1-2 times per day), an automated VR test on the FYI bot's Pixel with the viewer set to Daydream View will not enter VR.

In WebVR tests, this can be seen with the following line that gets output after requestPresent is called with a user gesture:

chromium: [INFO:CONSOLE(0)] "Uncaught (in promise) NotAllowedError: Presentation request was denied.", source: file:///storage/emulated/0/chromium_tests_root/chrome/test/data/android/webvr_instrumentation/html/test_screen_taps_registered.html (0)

In VR Shell tests, this can be seen with VrShellDelegate.isInVr not evaluating to true within a reasonable time after VrShellDelegate.enterVrIfNecessary is called.

Since it's only happening when the viewer is Daydream View, my initial thought is that this is standard DON flow skipping weirdness, but I'm not certain about that yet.