Fix asyncRescaleAndReadPixelsYUV420 fallback w/out GL_EXT_texture_rg.

Copying the color type from the RTCs is incorrect because we may have
fallen back to GL_RGBA8 if GL_R8 is not renderable.

Change-Id: Ie8effabfe60c2410d200b1775f463d5edb13fe81
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/267179
Commit-Queue: Brian Salomon <bsalomon@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
Auto-Submit: Brian Salomon <bsalomon@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
1 file changed