Remove simple_util::GetMTime from simple cache.

Remove simple_util::GetMTime from simple cache.

With base::PlatformFile::GetPlatformFileInfo now being high resolution, there's
no need for this system specific cruft in the simple disk cache.

R=clamy,pasko
BUG=None

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=220123

[gavinp, 2013-08-07 19:13:36]

This CL depends on https://codereview.chromium.org/22582009/

clamy: PTAL.

pasko: FYI. Probably conflicts with a CL you're working on.

[pasko, 2013-08-07 19:18:45]

lgtm thanks!

this seems to be an easy conflict

[clamy, 2013-08-08 14:42:56]

On 2013/08/07 19:18:45, pasko wrote:
> lgtm thanks!
> 
> this seems to be an easy conflict

lgtm

Thanks Gavin! It's nice to see that go in base.

[gavinp, 2013-08-28 17:52:08]

I rebased this, and I'll let it bake on try before landing. This should be fine,
but see https://codereview.chromium.org/22929021/ for something scary about the
actual implementations here.

[commit-bot: I haz the power, 2013-08-28 19:06:26]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gavinp@chromium.org/22571011/19001

[commit-bot: I haz the power, 2013-08-29 00:09:27]

Change committed as 220123