Revert of Remove dependency on content from remoting_host.

Revert of Remove dependency on content from remoting_host. (patchset #5 id:160001 of https://codereview.chromium.org/929493002/)

Reason for revert:
Compile failure on Linux ChromiumOS Ozone Builder:
http://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Ozone%20Builder/builds/11867

Original issue's description:
> Remove dependency on content from remoting_host.
>
> The host was depending on content just to access content::BrowserThread.
> It's cleaner to just pass the references to the threads explicitly.
>
> BUG=458581
>
> Committed: https://crrev.com/d5197934178ef0da1b630792cfbda8ddb6b34388
> Cr-Commit-Position: refs/heads/master@{#316648}

TBR=kelvinp@chromium.org,sergeyu@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=458581
Committed: https://crrev.com/34ca873ecd8905a90f9acfc6e840fb84671895af
Cr-Commit-Position: refs/heads/master@{#316661}

[Charlie Reis, 2015-02-17 21:43:52]

Created Revert of Remove dependency on content from remoting_host.

[commit-bot: I haz the power, 2015-02-17 21:44:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/923773003/1

[commit-bot: I haz the power, 2015-02-17 21:46:34]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-17 21:47:05]

Patchset 1 (id:??) landed as
https://crrev.com/34ca873ecd8905a90f9acfc6e840fb84671895af
Cr-Commit-Position: refs/heads/master@{#316661}