GrSurfaceContext::read/writePixels takes GrPixmap

Change readPixels contract to allow unknown->unknown AT reads, but
fail if one side is unknown and the other isn't (and update GPU read
pixels test accordingly).

Also, ProxyUtils::MakeTextureProxyViewFromData takes GrPixmap.

Bug: skia:8862
Change-Id: I771c154833408e666f860413c1a711714696326d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/347196
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
31 files changed