https://chromium-review.googlesource.com/c/chromium/src/+/671369 added a depency from src/build to src/testing. The dependency was probably there before, but this change bubbled up into building v8 and blocks the deps roll, e.g.:
https://chromium-review.googlesource.com/c/v8/v8/+/677977

How should we structure dependencies across projects from now on? Some thoughts:

1) Have all build config files to be under src/build and maybe enforce this with a PRESUBMIT check in the future (maybe allow whitelisting exceptions to this?).
2) Make subprojects like V8 pull all other required directories except src/build as dependencies.
3) Let subprojects fork the required files from other directories.

Other ideas?

1) Would be easiest for subproject maintainers like me. I dislike 2) if the directories are large file graveyards with tons of things the subprojects actually don't need. 3) can server as short-term workaround, but essentially gathers technical dept.