Add GrSurfaceProxyView and add support for it on GrRenderTargetContext.

Bug: skia:9556
Change-Id: I681c364cef6867feb0ae06a53cd7d264d7163e35
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/249879
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
5 files changed