Revert of Fix failing tests with ChannelMojo enabled. (patchset #3 id:300001 of https://codereview.chromium.org/1768903002/ )

Reason for revert:
This CL is causing failures in ipc_mojo_unittests.

See:
https://build.chromium.org/p/chromium.linux/builders/Linux%20Tests%20%28dbg%29%281%29/builds/52715
https://build.chromium.org/p/chromium.linux/builders/Linux%20Tests%20%28dbg%29%281%29%2832%29/builds/26588

Original issue's description:
> Fix failing tests with ChannelMojo enabled.
>
> This ChannelMojo to:
> - take a ScopedMessagePipeHandle instead of a string token so an
>   in-process renderer can be passed the message pipe directly;
> - send brokered attachments as mojo handles; and
> - offer messages to AttachmentBroker.
>
> This also fixes and re-enables ipc_channel_mojo_unittest.cc.
>
> BUG=579813
>
> Committed: https://crrev.com/013cfed7ecf91b0700bec7147631d4fbedb6b64e
> Cr-Commit-Position: refs/heads/master@{#380294}

TBR=rockot@chromium.org,tsepez@chromium.org,ben@chromium.org,sammc@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=579813

Review URL: https://codereview.chromium.org/1784773002

Cr-Commit-Position: refs/heads/master@{#380325}

0 files changed, 0 insertions, 0 deletions