Revert of Revert of Re-enable ChannelMojo

Revert of Revert of Re-enable ChannelMojo (patchset #1 id:1 of https://codereview.chromium.org/1029263008/)

Reason for revert:
It seems it was not guilty.
According to Android Tests (dbg) bot, revering #322094 was enough.

Original issue's description:
> Revert of Re-enable ChannelMojo (patchset #1 id:1 of https://codereview.chromium.org/1021393002/)
>
> Reason for revert:
> speculative revert for "Too many open files" on various Mac bots.
> e.g. http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Mac10.9/builds/17511/steps/webkit_tests/logs/stdio
>
> Original issue's description:
> > Re-enable ChannelMojo
> >
> > It was disabled due to crbug.com/466814 that is now fixed.
> > It's time to turn it on again.
> >
> > R=viettrungluu@chromium.org
> > BUG=466814, 377980
> >
> > Committed: https://crrev.com/c99c93842fa50f85888d069f0be962462f92a643
> > Cr-Commit-Position: refs/heads/master@{#322092}
>
> TBR=viettrungluu@chromium.org,morrita@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=466814, 377980
>
> Committed: https://crrev.com/9e4596122cda5dbc959895b53679e14df45658b5
> Cr-Commit-Position: refs/heads/master@{#322113}

TBR=viettrungluu@chromium.org,morrita@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=466814, 377980
Committed: https://crrev.com/a73fbeaa64b86689506bbbb9a2473460b976dbf8
Cr-Commit-Position: refs/heads/master@{#322118}

[tkent, 2015-03-25 05:58:53]

Created Revert of Revert of Re-enable ChannelMojo

[commit-bot: I haz the power, 2015-03-25 05:59:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1031083002/1

[commit-bot: I haz the power, 2015-03-25 06:00:03]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-25 06:01:03]

Patchset 1 (id:??) landed as
https://crrev.com/a73fbeaa64b86689506bbbb9a2473460b976dbf8
Cr-Commit-Position: refs/heads/master@{#322118}