Expand code macros in _finalize_frame

With this CL, _generate_test finally does what it's suppose to, and no
more. Everything unrelated to generating the test files have been moved
out.

Bug: 330885075
Change-Id: I1f295966503cc280a8eaaea84a35117faaa2a8b8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5373590


Reviewed-by: Andres Ricardo Perez <andresrperez@chromium.org>
Commit-Queue: Jean-Philippe Gravel <jpgravel@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1282138}