Hey Boyuan,

thanks for looking at this issue! I agree it's quite confusing, but I finally
found out what's going on.

*****

Let me provide a new summary of Mesa releases & this problem:

1) Accelerated VP9 decoding in Chromium is broken with 18.1 & 18.2.
2) Video Acceleration DOESN'T WORK in Chromium with 18.3.0 - 18.3.3
3) Accelerated VP9 decoding in Chromium is broken with 18.3.4 & 19.0.

By "broken" I mean corrupted colors.

*****

Earlier confusion was due to the commit 55e7de7b1935 ("radeonsi: enable vcn
jpeg decode for raven") EXPOSING a bug 109107 which was related to reporting
profiles. That commit STOPPED Chromium from using Video Acceleration and made
it report following errors:
[21202:21202:0317/122002.223002:ERROR:vaapi_wrapper.cc(587)] :
vaQueryConfigProfiles returned: 14
[21202:21202:0317/122002.223045:ERROR:vaapi_wrapper.cc(587)] :
vaQueryConfigProfiles returned: 14

Bug 109107 got fixed with the commit 21cdb828a3f4 ("st/va: fix the incorrect
max profiles report") and since then:
1) Chromium uses Video Acceleration again
2) I see corrupted VP9 YouTube colors again

So the commit 55e7de7b1935 ("radeonsi: enable vcn jpeg decode for raven")
DIDN'T FIX anything but has only hidden the original problem. It stopped
Chromium from using Video Acceleration including VP9 hardware decoding.

*****

The problem is still there (in the 18.3.4, 19.0 and master) and needs to be
fixed :(