Long path names can cause test failures on bots,
due to max path name limitations by OS, like  Issue 906964 .

Currently path name lengths are not checked at presubmit for:
- Non-WPT test path names (IIUC), and
- Virtual test path names. Full path name like "virtual/foo/external/wpt/bar/baz.html" should be checked, even if there are no "virtual/foo/external/wpt/bar/baz.html" file in the repository, as the test runner can generate files like "virtual/foo/external/wpt/bar/baz-pretty-diff.html".

Not sure what max length value to be used.
The limit of WPT test path names is 150:
https://web-platform-tests.org/writing-tests/general-guidelines.html
(i.e. max 163 if "external/wpt/" part is included)

In the case of  Issue 906964 , the test name
"virtual\off-main-thread-worker-script-fetch\external\wpt\referrer-policy\no-referrer-when-downgrade\meta-referrer\same-origin\http-http\worker-request\keep-origin-redirect\insecure-protocol.http.html"
(199 chars) caused the path length limit exceeded.