In this tryjob:
https://ci.chromium.org/p/chromium/builders/luci.chromium.try/win_optional_gpu_tests_rel/5425

it was observed that EXT_disjoint_timer_query isn't exposed in either the passthrough or validating command decoders with ANGLE's D3D9 backend.

I think this extension used to work on this configuration before these extensions were disabled in  Issue 808744 , so filing this to investigate if time permits.