Add Skia/Metal to the Chromium build

Keep it behind a skia_use_metal flag for the moment.

Put the Metal sources in a separate place from skia_util_mac.mm, because
Metal uses ARC and skia_util_mac.mm uses explicit reference counting.

Bug: 952063
Change-Id: I601b3c9814b4beaf6a091871ba4dc2592c2fc498
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1565387
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: ccameron <ccameron@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652229}
1 file changed