12:47:49.681 2173 worker/3 virtual/threaded/fast/scroll-behavior/smooth-scroll/mousewheel-scroll-interrupted.html output stderr lines:
12:47:49.681 2173   Xlib:  extension "RANDR" missing on display ":100".
12:47:49.681 2173   
12:47:49.681 2173   DevTools listening on ws://127.0.0.1:55471/devtools/browser/0d9947f7-5dd6-49ec-b36d-2eed5f493c98
12:47:49.681 2173   [2186:2249:1121/124350.260999:ERROR:instance.cc(49)] Unable to locate service manifest for metrics
12:47:49.681 2173   [2186:2249:1121/124350.261050:ERROR:service_manager.cc(889)] Failed to resolve service name: metrics
12:47:49.684 4986 [6/6] virtual/threaded/fast/scroll-behavior/smooth-scroll/mousewheel-scroll-interrupted.html failed unexpectedly (test timed out)

Probably all of the lines of that output are irrelevant except "virtual/threaded/fast/scroll-behavior/smooth-scroll/mousewheel-scroll-interrupted.html failed unexpectedly (test timed out)". (The rest looks like normal Linux log spam.)

I'm confused about how to get more information on this. The flakiness dashboard is unhelpful (only shows flakes for all layout tests; can't focus on this specific test).

Are there multiple failures or just this one? Please provide more information (and hopefully, a link to the flakiness dashboard that shows the multiple failures).

Removing from sheriff queue until more information is provided.

Sandra, please take a look at these.