Revert of Enable ChannelMojo

Revert of Enable ChannelMojo (patchset #3 id:40001 of https://codereview.chromium.org/857483004/)

Reason for revert:
This is breaking a lot of things (He's dead jim pages, extensions, and other things). See issue 462026.

Original issue's description:
> Enable ChannelMojo
>
> As we addressed certain amount of the performance problem,
> it's time to give it another try.
>
> R=viettrungluu@chromium.org
> BUG=377980
>
> Committed: https://crrev.com/a06cd1b2fe83b51b0874ca504066f00a17192026
> Cr-Commit-Position: refs/heads/master@{#313184}

TBR=viettrungluu@chromium.org,morrita@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=377980
Committed: https://crrev.com/779310e250bee978cc6aaf68ef4dede4bd742357
Cr-Commit-Position: refs/heads/master@{#320394}

[Mr4D (OOO till 08-26), 2015-03-12 22:32:40]

Created Revert of Enable ChannelMojo

[commit-bot: I haz the power, 2015-03-12 22:33:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1002973002/1

[commit-bot: I haz the power, 2015-03-12 22:33:55]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-12 22:34:22]

Patchset 1 (id:??) landed as
https://crrev.com/779310e250bee978cc6aaf68ef4dede4bd742357
Cr-Commit-Position: refs/heads/master@{#320394}

[Hajime Morrita, 2015-03-12 23:29:09]

On 2015/03/12 22:34:22, I haz the power (commit-bot) wrote:
> Patchset 1 (id:??) landed as
> https://crrev.com/779310e250bee978cc6aaf68ef4dede4bd742357
> Cr-Commit-Position: refs/heads/master@{#320394}

lgtm.

[alexmos, 2015-03-13 00:12:48]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1000173003/ by alexmos@chromium.org.

The reason for reverting is: Suspecting that this is breaking a bunch of
Phishing*, DomSerializer*, and ResourceFetcher* tests on various bots.  For
example:
https://build.chromium.org/p/chromium.linux/builders/Linux%20Tests%20%28dbg%2...
and
https://chromium.googlesource.com/chromium/src/+log/7798a5020aca61cf96eb783fb...

(blamelist intersection is r320394:r320395)

Sample output (*SerializeDocumentWithDownloadedIFrame):

[28371:28482:0312/162210:38108696320:FATAL:scoped_ipc_support.cc(33)] Check
failed: (init_count_ == 0 && !io_thread_task_runner_) || io_thread_task_runner_
== io_thread_task_runner.
#0 0x0000f47ce8c4 base::debug::StackTrace::StackTrace()
#1 0x0000f482ff71 logging::LogMessage::~LogMessage()
#2 0x0000f2b503d3 IPC::(anonymous namespace)::IPCSupportInitializer::Init()
#3 0x0000f2b501cd IPC::ScopedIPCSupport::ScopedIPCSupport()
#4 0x0000e9e5ddf6 content::ChannelInit::Init()
#5 0x0000e9990577 content::MojoApplication::OnActivate()
#6 0x0000e9990cb1
_Z20DispatchToMethodImplIN7content15MojoApplicationEMS1_FvRKN4base14FileDescriptorEEJS3_EJLj0EEEvPT_T0_RK5TupleIJDpT1_EE13IndexSequenceIJXspT2_EEE
#7 0x0000e9990bd9
_Z16DispatchToMethodIN7content15MojoApplicationEMS1_FvRKN4base14FileDescriptorEEJS3_EEvPT_T0_RK5TupleIJDpT1_EE
#8 0x0000e99909ce MojoMsg_Activate::Dispatch\u003C>()
#9 0x0000e9990302 content::MojoApplication::OnMessageReceived()
#10 0x0000e99079ef content::ChildThreadImpl::OnMessageReceived()
#11 0x0000f31f7ee4 IPC::ChannelProxy::Context::OnDispatchMessage()

.