Revert of [Chromecast] Change chromecast_branding to public (patchset #6 id:100001 of https://codereview.chromium.org/1262673004/)

Reason for revert:
Revert the CL temporary for TOT build. Checked in again once the internal CLs are approved.

Original issue's description:
> [Chromecast] Change chromecast_branding to public
>
> Change chromecast_branding from Chrome/Chromium to
> public/internal/google in gyp file. "public" is the same as "Chromium"
> and the other two are considered as "Chrome".
>
> BUG=
>
> Committed: https://crrev.com/0f46bd94566380a99ecda0753f659b7e114e3d3d
> Cr-Commit-Position: refs/heads/master@{#341016}

TBR=lcwu@chromium.org,gunsch@chromium.org,byungchul@chromium.org,slan@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/1266723002

Cr-Commit-Position: refs/heads/master@{#341034}
8 files changed