Move test code out of header into CPP file.

This test code is templated, but not really generic (it's only meant to
work with two specific classes) so it doesn't need to live in a header.

Change-Id: I38d4f2cc9637207eca678fc81ff35ebbd7e69fce
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/303656
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
2 files changed