Canvas low latency: a few more cleanups

This CL has a few side cleanups to crrev.com/c/1321773, taken
out for clarity.
- Renames class
 CanvasResourceProviderRamGpuMemoryBuffer to
 CanvasResourceProviderBitmapGpuMemoryBuffer
- Moves calculation of |gl_format| to where it's used.

Bug: 902585
Change-Id: Ia0f0393425afd60ad98dbdd38f3ef5bc0d5e9e2f
Reviewed-on: https://chromium-review.googlesource.com/c/1321749
Commit-Queue: Miguel Casas <mcasas@chromium.org>
Reviewed-by: Fernando Serboncini <fserb@chromium.org>
Reviewed-by: Andres Calderon Jaramillo <andrescj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606229}
3 files changed