Findit identified the culprit r555993 with confidence 70.0% in the config "chromium.memory / Linux ChromiumOS MSan Tests"
based on the flakiness trend:

https://findit-for-me.appspot.com/waterfall/flake?key=ag9zfmZpbmRpdC1mb3ItbWVytAELEhdNYXN0ZXJGbGFrZUFuYWx5c2lzUm9vdCJ-Y2hyb21pdW0ubWVtb3J5L0xpbnV4IENocm9taXVtT1MgTVNhbiBUZXN0cy83MDIzL2NvbnRlbnRfYnJvd3NlcnRlc3RzL1EyOXRjRzl6YVhSdmNrVjJaVzUwUVdOclFuSnZkM05sY2xSbGMzUXVWRzkxWTJoVGRHRnlkQT09DAsSE01hc3RlckZsYWtlQW5hbHlzaXMYAQw


Automatically posted by the findit-for-me app (https://goo.gl/Ot9f7N).
Feedback is welcome! Please use component Tools>Test>FindIt>Flakiness

https://logs.chromium.org/v/?s=chromium%2Fbb%2Fchromium.memory%2FLinux_ChromiumOS_MSan_Tests%2F7023%2F%2B%2Frecipes%2Fsteps%2Fcontent_browsertests%2F0%2Flogs%2FCompositorEventAckBrowserTest.PassiveTouchStartBlockingTouchEnd%2F0

It looks like hovering_ is uninitialized? Not sure why it just started flaking.

https://cs.chromium.org/chromium/src/ui/events/event.h?type=cs&sq=package:chromium&l=757

This was written by nzolghadr@chromium.org so I'm assigning to him.

 Issue 840159  has been merged into this issue.

This test hasn't failed in the last 20+ runs, so removing from sheriff queue.

Fady, that field at least in the code path you are talking about is being initialized here
https://cs.chromium.org/chromium/src/ui/events/blink/blink_event_util.cc?sq=package:chromium&dr&l=616

Do you still think an initialization in the class itself would resolve this issue?