This reflects Dawn and Metal functionality.
Implement a FramebufferOnly flag on GrSurface and GrBackendRenderTarget.
Forward the state from GrBackendRenderTarget to GrSurface.
Check the GrSurface flag in GrGpu::readPixels() and GrGpu::writePixels()
and early-return.
Change-Id: I27d3c9c912b366791bfd0e1db49638d8925742f3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/262802
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
3c0a50f038