We've had large numbers of shutdown hangs with the Windows H.264 decoder stuck
calling IMFTransform::ProcessOutput(), blocking shutdown. I can reproduce this
with videos with dimensions less than 32 pixels.
Chrome also encountered this with the WMF decoder:
https://bugs.chromium.org/p/chromium/issues/detail?id=373288
The WMF H.264 Decoder is documented to have a minimum resolution of 48x48 pixels.
So this patch causes us to reject H.264 files with either width or height less
than 48 pixels.
I have been able to play files down to 34x34 pixels on Windows 10, but it seems
safest to just follow the what's documented in MSDN, and reject files that are
smaller than the documented minimum.
MozReview-Commit-ID: 5peP6UGnAaB
--HG--
extra : rebase_source : 6e29812642bc3f8ca0f5b39b36064a6d50e09ea7
Chris Pearce