The test changes had a function pointer type mismatch on some platforms,
causing build failures. Revert the tests changes and keep only the fix
for the buffer overflow.

BUG=595836

Change-Id: Ia2db42dc7b19fc46676addaf8ad36f29d9bf69e5
Reviewed-on: https://chromium-review.googlesource.com/334396Reviewed-by: Corentin Wallez <cwallez@chromium.org>