I've inspected 3 builds.
The logs from the two above are not helpful:
=== LOG STARTS ===
00:34:50.491 1972 [15817/58022] http/tests/inspector/network/resource-priority.html failed unexpectedly (text diff)
00:34:50.488 2876 worker/0 http/tests/inspector/network/resource-priority.html failed:
00:34:50.488 2876 worker/0  text diff
=== LOG ENDS ===

The third one (https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Win7%20%28dbg%29/builds/9645) has also (in addition to the log above):
=== LOG STARTS ===
21:06:06.242 4364 worker/5 http/tests/inspector/network/resource-priority.html output stderr lines:
21:06:06.242 4364   [7296:3244:0425/210555.959:8575000:INFO:media_foundation_video_encode_accelerator_win.cc(329)] Windows versions earlier than 8 are not supported.
=== LOG ENDS ===

The test 
https://chromium.googlesource.com/chromium/src/+blame/ebd1c7d184fd1979b0eb0590665fe2695fc353f7/third_party/WebKit/LayoutTests/http/tests/inspector/network/resource-priority.html

has been touched recently in https://codereview.chromium.org/2826213003. 

The CL from #2 was built in https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Win7%20%28dbg%29/builds/9642.

The resource-priority.html failed in 9642, but did not fail in 9641.

Taking ownership.  Definitely caused by my CL and not caught by the try bots or most tests because the console log warning is racy (will only show up if the layout test takes longer than the time needed to trigger it).

Fix should be trivial but I'll revert, fix and re-land.

Great, thank you for looking into this!
Please revert.

Revert submitted: https://codereview.chromium.org/2843013002/

Revert has landed