Reorganize Protected content utilities to be more reusable

I'm adding a Protected content slide to Viewer and would like to share this code.

This CL just moves the utilities out of ProtectedTest.cpp and VkProtectedContextTest.cpp, removes the uses of the Reporter class and adds SkISize dimension parameters.

Change-Id: I646557e8b55256c6a1a56a5f975a1d9bedf64a37
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/733436
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
6 files changed