[Android] MaybeWaitOnFence doesn't signal with videos/Impeller.

[jonahwilliams]

Running the Flutter Gallery app with Impeller/Vulkan and the YUV sampler patch from @chinmaygarde

Logs are full of

E/ImageReaderSurfaceProducer( 3117): acquireLatestImage image's fence was never signalled.
E/ImageReaderSurfaceProducer( 3117): acquireLatestImage image's fence was never signalled.
E/ImageReaderSurfaceProducer( 3117): acquireLatestImage image's fence was never signalled.
E/ImageReaderSurfaceProducer( 3117): acquireLatestImage image's fence was never signalled.
E/ImageReaderSurfaceProducer( 3117): acquireLatestImage image's fence was never signalled.
E/ImageReaderSurfaceProducer( 3117): acquireLatestImage image's fence was never signalled.
E/ImageReaderSurfaceProducer( 3117): acquireLatestImage image's fence was never signalled.
E/ImageReaderSurfaceProducer( 3117): acquireLatestImage image's fence was never signalled.
E/ImageReaderSurfaceProducer( 3117): acquireLatestImage image's fence was never signalled.
E/ImageReaderSurfaceProducer( 3117): acquireLatestImage image's fence was never signalled.
E/ImageReaderSurfaceProducer( 3117): acquireLatestImage image's fence was never signalled.
E/ImageReaderSurfaceProducer( 3117): acquireLatestImage image's fence was never signalled.
E/ImageReaderSurfaceProducer( 3117): acquireLatestImage image's fence was never signalled.
E/ImageReaderSurfaceProducer( 3117): acquireLatestImage image's fence was never signalled.
E/ImageReaderSurfaceProducer( 3117): acquireLatestImage image's fence was never signalled.

CPU profile looks like:

Despite never signalling, we spend 50 ms out of 180ms CPU time checking it. Is this working in other cases, because it seems like its extraordinarily expensive for something that isn't working at all.

See also: #142153

[johnmccutchan]

I've asked Android folks what is expected here.

[jonahwilliams]

Marking this as P1 as I understand you are working on it? Or at least asking about it, and we can figure out what to do afterwards.