Revert of Eliminate kMojoChannelToken usage for render processes

Revert of Eliminate kMojoChannelToken usage for render processes (patchset #6 id:100001 of https://codereview.chromium.org/2201183005/ )

Reason for revert:
Speculative revert for failures on https://build.chromium.org/p/chromium.win/builders/Win7%20Tests%20%281%29 - can't repro locally but wanna see if this greens the tests.

Original issue's description:
> Eliminate kMojoChannelToken usage for render processes
> 
> Changes RenderProcessHostImpl to connect its IPC Channel
> by requesting a nominal IPC::mojom::ChannelBootstrap
> interface from its shell::Connection to the render process.
> 
> Changes ChildThreadImpl to support binding such requests
> by fusing them to its local IPC Channel if the (now deprecated)
> kMojoChannelToken was not provided.
> 
> BUG=623396
> R=ben@chromium.org
> 
> Committed: https://crrev.com/7a7f8f7e6977500d09270ff9d9b3817dda5e5b8a
> Committed: https://crrev.com/ff1b853cb6bfc3d5402fc970b2d856cbe73418cc
> Cr-Original-Commit-Position: refs/heads/master@{#410656}
> Cr-Commit-Position: refs/heads/master@{#410699}

TBR=ben@chromium.org,huangs@chromium.org,jschuh@chromium.org,tsepez@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=623396

[Ken Rockot(use gerrit already), 2016-08-10 17:01:00]

The CQ bit was checked by rockot@chromium.org

[Ken Rockot(use gerrit already), 2016-08-10 17:01:01]

Created Revert of Eliminate kMojoChannelToken usage for render processes

[commit-bot: I haz the power, 2016-08-10 17:02:29]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Tom Sepez, 2016-08-10 17:11:22]

RS LGTM

[Tom Sepez, 2016-08-10 17:11:23]

RS LGTM

[commit-bot: I haz the power, 2016-08-10 18:41:44]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-08-10 18:41:47]

Try jobs failed on following builders:
  linux_android_rel_ng on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/linux_androi...)

[Ken Rockot(use gerrit already), 2016-08-10 18:48:33]

The CQ bit was checked by rockot@chromium.org

[commit-bot: I haz the power, 2016-08-10 18:49:19]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-10 21:22:12]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-08-10 21:22:13]

Try jobs failed on following builders:
  linux_android_rel_ng on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/linux_androi...)

[Ken Rockot(use gerrit already), 2016-08-10 23:57:22]

The CQ bit was checked by rockot@chromium.org

[commit-bot: I haz the power, 2016-08-10 23:58:08]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-11 00:06:24]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-08-11 00:06:28]

Try jobs failed on following builders:
  chromium_presubmit on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[Ken Rockot(use gerrit already), 2016-08-11 00:35:09]

Actually I'm not going to revert this. The Win breakage is unfortunate but
clearly not a blocker. I will submit a separate CL which reverts only RPHI
behavior to green the bot while I'm OOO.