Another failure that appeared at the same time is:

viz_browser_tests failing on chromium.memory/Linux Chromium OS ASan LSan Tests (1)

More details: 
- interactive_ui_tests: WebUiScreenLockerTest.TestFullscreenExit: LeakSanitizer: detected memory leaks
- viz_browser_tests: PermissionRequestManagerBrowserTest.BackgroundTabNavigation: Various check failures?

First occurrence:
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Linux%20Chromium%20OS%20ASan%20LSan%20Tests%20%281%29/28840

Potential CLs (WebKit with code change) that cause this:

(1) Resolve :root and table-cell currentcolor using background box's style
  https://chromium-review.googlesource.com/1203373

(2) Implement script and style attr/elem CSP directives
  https://chromium-review.googlesource.com/1181050

CCing authors.

Since (1) 1203373 is relatively small, I'm planning to speculatively revert it to see if ASan problem goes away. If not then (2) 1181050 will be reverted.

Actually, it makes more sense to revert the large CL (2) first, since:
- The odds of it causing / revealing bug is larger.
- If this turns out to be the culprit, it's more likely that reverting will be infeasible later.

The revert CL for (2): https://chromium-review.googlesource.com/c/chromium/src/+/1205392

Now we monitor https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Linux%20Chromium%20OS%20ASan%20LSan%20Tests%20%281%29

If problem clears up then (2) likely has leaks or other checking failure.  If problem remains, then we revert (1) as well.

The {interactive_ui_tests, viz_browser_tests} failures disappeared before my revert has a chance to run. May as well reland (2).

Actually, should reland later, so the revert CL gets its own ASan LSan run.

Relanded the CL: https://chromium-review.googlesource.com/c/chromium/src/+/1205478

Looks like this is gone?