Revert of Delete transformadapter.cc and transformadapter.h. (patchset #2 id:20001 of https://codereview.webrtc.org/2368243002/ )

Reason for revert:
This change broke a downstream application.

Original issue's description:
> Delete transformadapter.cc and transformadapter.h.
>
> BUG=webrtc:6424
>
> Committed: https://crrev.com/2c3c3e27321e4b616bd1222857b2882befc485e3
> Cr-Commit-Position: refs/heads/master@{#14541}

TBR=perkj@webrtc.org,pthatcher@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:6424

Review-Url: https://codereview.webrtc.org/2400443003
Cr-Original-Commit-Position: refs/heads/master@{#14543}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 8e7577c468e6d8dad76f8befdb57f759b346a032
4 files changed