Split up Codec 'check' into multiple helper functions.

This function was already divided into several different tests, but each
part relied on various bits and pieces from the others. This CL splits
it apart into smaller functions which should be easier to reason about.

This CL also fixes a handful of variable shadowing issues in the code.

Change-Id: Icfe189ae5fdf29913c1d94a6b5df9432442d648c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/438658
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
1 file changed