This issue
https://sheriff-o-matic.appspot.com/chromium/examine/chromium.webkit.WebKit%20Linux%20Trusty%20Leak.webkit_layout_tests.

is being caused by this CL:
https://chromium-review.googlesource.com/c/chromium/src/+/1050547

But that's not in the blame range in sheriff-o-matic:
https://chromium.googlesource.com/chromium/src/+log/c71fcaeb63583fcbf854f7c4a99a8a124037815a%5E..6358e09882ccfd713f02b93b968711d5de95bb24?pretty=fuller&n=