Revert of Revert "Remove CpuMonitor and related, unused, code."

Revert of Revert "Remove CpuMonitor and related, unused, code." (patchset #1 id:1 of https://codereview.webrtc.org/1287913004/ )

Reason for revert:
(retrying with my webrtc account...)
The reason for reverting is: Re-landing the change that removes the CpuMonitor class after having fixed the build issue in Chromium..

Original issue's description:
> Revert "Remove CpuMonitor and related, unused, code."
>
> This reverts commit 1a24012680f25440aa1d117373df2af14cdc2fc1.
>
> TBR=tommi@webrtc.org,pthatcher@webrtc.org
> BUG=
>
> This breaks
> http://build.chromium.org/p/chromium.webrtc.fyi/builders/Linux/builds/20148/steps/compile/logs/stdio
>
> Committed: https://chromium.googlesource.com/external/webrtc/+/a472e968c95fb14e63ec42f453551d0967573ea8

TBR=pthatcher@webrtc.org,guoweis@webrtc.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Committed: https://crrev.com/048e80cacab128280c37c3e0574873cde8544410
Cr-Commit-Position: refs/heads/master@{#9733}

[tommi, 2015-08-19 10:59:38]

Created Revert of Revert "Remove CpuMonitor and related, unused, code."

[commit-bot: I haz the power, 2015-08-19 10:59:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1290033005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1290033005/1

[commit-bot: I haz the power, 2015-08-19 11:00:01]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-19 11:00:13]

Patchset 1 (id:??) landed as
https://crrev.com/048e80cacab128280c37c3e0574873cde8544410
Cr-Commit-Position: refs/heads/master@{#9733}