Remove SkImage::MakeFromYUVATexturesCopyToExternal

It's no longer used by Chrome.

Inline helper that draws yuva->rgba into the now single use case.

Move yuva proxy making helper from SkImage_GpuBase to SkImage_GpuYUVA
since it is only used there now.

Remove gm that tested the API and associated helper code in YUVUtils.

Bug: skia:10632
Change-Id: If6bd49befa1d1098bb6a268b9d856794f7eb80c3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/342077
Reviewed-by: Adlai Holler <adlai@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
10 files changed