Reland of Move BUILD.public to public.bzl. (patchset #1 id:1 of https://codereview.chromium.org/1580923002/ )

Reason for revert:
Internal cl/111468120 is now ready to go.

Original issue's description:
> Revert of Move BUILD.public to public.bzl. (patchset #1 id:1 of https://codereview.chromium.org/1577353002/ )
>
> Reason for revert:
> Corresponding google-private changes not ready.
>
> Original issue's description:
> > Move BUILD.public to public.bzl.
> >
> > This allows building with bazel (see http://bazel.io).
> >
> > BUG=skia:
> > GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1577353002
> >
> > Committed: https://skia.googlesource.com/skia/+/eeebfff54877b24151570c4f02b2299e3f9ef967
>
> TBR=benjaminwagner@google.com,mtklein@google.com
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/330043c073de2ee63faa1caa3cb4170da68a79f2

TBR=mtklein@google.com,iroth@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/1584563004
1 file changed