See https://developer.android.com/ndk/guides/pgo

I think for both code coverage and PGO we would need to manual ensure the profile is written, by callin __llvm_profile_set_filename() and __llvm_profile_write_file(). I'm not sure if its actually the same function for both pgo and code coverage, but the same principle applies.
Assuming we are using webdriver to drive the test / profiling, then our custom webdriver shutdown logic might offer a good hook opportunity.