Reland of ll third_party/custom_tabs_client (patchset #1 id:1 of https://codereview.chromium.org/1263983002/)
Reland of ll third_party/custom_tabs_client (patchset #1 id:1 of https://codereview.chromium.org/1263983002/)

Reason for revert:
hmm sorry this doesn't appear to have been the reason for issues on the bot. putting the roll back in.

Original issue's description:
> Revert of Roll third_party/custom_tabs_client (patchset #1 id:1 of https://codereview.chromium.org/1254383014/)
>
> Reason for revert:
> speculative revert, prevents clank roll downstream, see crbug.com/515457
>
> Original issue's description:
> > Roll third_party/custom_tabs_client
> >
> > Roll from 6bae8bf337d5c51184c0c01f5baca3e0858 to
> > 19d5cb35bece11876e8f34c17c6fdfd9bad.
> >
> > BUG=510083
> >
> > Committed: https://crrev.com/dc731ce3111a8d4f316e478601707cc33e70e542
> > Cr-Commit-Position: refs/heads/master@{#341048}
>
> TBR=yusufo@chromium.org,ianwen@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=510083
>
> Committed: https://crrev.com/66d3e303ded89c565e8fb33d8000044cdcf2b8c1
> Cr-Commit-Position: refs/heads/master@{#341100}

TBR=yusufo@chromium.org,ianwen@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=510083

Review URL: https://codereview.chromium.org/1252393003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#341104}

CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend