I'm trying to enable -Wimplicit-fallthrough for use_ozone=true builds (it even finds bugs: https://chromium-review.googlesource.com/c/chromium/src/+/899984)

So I enabled the warning locally, used the same gn args as the headless bot (I think it was an `import(build/args/headless.gni)` or similar), and ran `ninja -C out/gnozon`.

That seems to build a bunch of targets that aren't supposed to be built, which is imho a bug; if someone were to clean this up by removing references to targets that aren't supposed to build in this config from //BULD.gn that'd be good.

Building what the headless bot uses, which is "headless:headless headless:headless_browsertests headless:headless_example headless:headless_shell headless:headless_unittests headless_browsertests headless_unittests", works, but it's hard to remember a list like this for every build config, and it also didn't build everything where the new warning found bugs (namely, vr_shell -- which did build fine except for the new warning)


(original report: https://groups.google.com/a/chromium.org/forum/#!topic/ozone-dev/Rkwz9sd6VJk)


(similar: issue 808528)