The files in validations are test data for mojo conformance tests, which validate the memory layout of mojo messages.
Run validation tests using the following command:
autoninja -C out/Default mojo_unittests out/Default/bin/run_mojo_unittests --gtest_filter=ValidationTest.*
Note that you do not need to rebuild after changing the test data.
ValidationTest.*
to ensure that tests work as expected.