Revert of Revert of Use CLOCK_REALTIME_COARSE when available.

Revert of Revert of Use CLOCK_REALTIME_COARSE when available. (patchset #1 id:1 of https://codereview.chromium.org/1154783003/)

Reason for revert:
Experimental reland

Original issue's description:
> Revert of Use CLOCK_REALTIME_COARSE when available. (patchset #1 id:1 of https://codereview.chromium.org/1151283005/)
> 
> Reason for revert:
> [Sheriff] This leads to several failures in chromium and blocks our roll:
> https://codereview.chromium.org/1154363002/
> 
> Bisect (https://codereview.chromium.org/1152553004/) points to this CL.
> 
> Please add the failing chromium trybot on a reland of this CL.
> 
> Original issue's description:
> > Use CLOCK_REALTIME_COARSE when available.
> >
> > On systems that have CLOCK_REALTIME_COARSE with good enough resolution,
> > we can avoid making a system call to get the current time; it's serviced
> > from the vDSO.
> >
> > This is v2 of the patch.  v1 can be found at [0] but was reverted in [1]
> > because of Chromium sandbox restrictions.  The necessary changes have
> > been applied upstream in [2].
> >
> > [0] https://codereview.chromium.org/1125003002
> > [1] https://codereview.chromium.org/1130083003
> > [2] https://codereview.chromium.org/1133653002
> >
> > BUG=
> > LOG=N
> >
> > Committed: https://crrev.com/28cea2b749f24ba33e6e0c8e343dd0d6258ee302
> > Cr-Commit-Position: refs/heads/master@{#28639}
> 
> TBR=jochen@chromium.org,bmeurer@chromium.org,ben@strongloop.com
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=
> 
> Committed: https://crrev.com/9cc183d8996948d71660a8b1dbddfeaee2f79ada
> Cr-Commit-Position: refs/heads/master@{#28656}

COMMIT=false

[Michael Achenbach, 2015-07-02 13:55:33]

Created Revert of Revert of Use CLOCK_REALTIME_COARSE when available.

[Michael Achenbach, 2015-07-02 13:57:45]

Do not commit yet - checking chromium trybots.

[Jakob Kummerow, 2015-07-02 14:49:34]

jkummerow@chromium.org changed reviewers:
+ jkummerow@chromium.org

[Jakob Kummerow, 2015-07-02 14:49:35]

Looks like the problem hasn't magically fixed itself.

https://codereview.chromium.org/1217543005/diff/1/src/base/platform/time.cc
File src/base/platform/time.cc (right):

https://codereview.chromium.org/1217543005/diff/1/src/base/platform/time.cc#n...
src/base/platform/time.cc:274: // not _too_ coarse.  Most kernels are built with
CONFIG_HZ=1000, providing
On my machine (Ubuntu Trusty):

$ cat /boot/config-$(uname -r) | grep CONFIG_HZ=
CONFIG_HZ=250

Which makes me doubtful how much impact this CL will have.

[Benedikt Meurer, 2015-09-09 18:53:29]

bmeurer@chromium.org changed reviewers:
- bmeurer@chromium.org