This moves more shared code into a simple templated helper function. It
will also allow us to call the parameter capture methods more easily
for mid-execution capture.

Refactoring change only.

Bug: angleproject:3611
Change-Id: I8d95a6230922dfa0403ba5c328df78735c765519
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1688508
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>