Revert of Implement IPC::ParamTraits<mojo::MessagePipeHandle>

Revert of Implement IPC::ParamTraits<mojo::MessagePipeHandle> (patchset #3 id:40001 of https://codereview.chromium.org/1051443003/)

Reason for revert:
Broke XP Tests (1):

https://build.chromium.org/p/chromium.win/builders/XP%20Tests%20%281%29/builds/36680/steps/ipc_mojo_unittests/logs/IPCChannelMojoTest.ParamTraitInvalidMesssagePipe

https://build.chromium.org/p/chromium.win/builders/XP%20Tests%20%281%29/builds/36680/steps/ipc_mojo_unittests/logs/IPCChannelMojoTest.ParamTraitValidMesssagePipe

Original issue's description:
> Implement IPC::ParamTraits<mojo::MessagePipeHandle>
>
> This allows MessagePipeHandle to be an IPC message member.
> Note that this assumes underlying channel being a ChannelMojo
> and can be used in content/  only after ChannelMojo settles.
>
> BUG=448190
> TEST=IPCChannelMojoTest.ParamTrait*
> R=viettrungluu@chromium.org
>
> Committed: https://crrev.com/5656ae68841a3e3ddaac75cf2983d9052d71d0d5
> Cr-Commit-Position: refs/heads/master@{#323265}

TBR=viettrungluu@chromium.org,morrita@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=448190
Committed: https://crrev.com/5b96979eb9c969061b94c5130c7214ca19bb7da3
Cr-Commit-Position: refs/heads/master@{#323322}

[mfomitchev1, 2015-04-01 20:36:05]

Created Revert of Implement IPC::ParamTraits<mojo::MessagePipeHandle>

[commit-bot: I haz the power, 2015-04-01 20:36:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1054723002/1

[Hajime Morrita, 2015-04-01 20:37:39]

On 2015/04/01 20:36:29, I haz the power (commit-bot) wrote:
> CQ is trying da patch. Follow status at
>  https://chromium-cq-status.appspot.com/patch-status/1054723002/1

lgtm

[commit-bot: I haz the power, 2015-04-01 20:38:06]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-01 20:38:46]

Patchset 1 (id:??) landed as
https://crrev.com/5b96979eb9c969061b94c5130c7214ca19bb7da3
Cr-Commit-Position: refs/heads/master@{#323322}