Improve time resolution in PlatformFileInfo.

Improve time resolution in PlatformFileInfo.

The Simple Cache uses directory and file mtimes at high granularity to
determine index freshness. As well, for linux process creation times,
a high resolution ctime from /proc is useful; so high resolution ctime
makes process creation times accurate.

R=darin

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=216478

[gavinp, 2013-08-07 16:42:02]

Darin,

Higher resolution times are always useful. They are particularly important for
https://codereview.chromium.org/22594007/ .

[darin (slow to review), 2013-08-07 18:17:28]

Is there anything needed for Windows?

LGTM

https://codereview.chromium.org/22582009/diff/19001/base/platform_file_posix.cc
File base/platform_file_posix.cc (right):

https://codereview.chromium.org/22582009/diff/19001/base/platform_file_posix....
base/platform_file_posix.cc:405: const time_t last_modified_sec =
file_info.st_mtime;
should there be a TODO here to investigate the best solution for OS_NACL?

[gavinp, 2013-08-07 18:24:33]

On 2013/08/07 18:17:28, darin wrote:
> Is there anything needed for Windows?

Windows is already using FILE_TIME, which has 100ns resolution, it does the
conversion rounding to the nearest microsecond. See
anon::FileTimeToMicroseconds() in time_win.cc.

> 
> LGTM
> 
>
https://codereview.chromium.org/22582009/diff/19001/base/platform_file_posix.cc
> File base/platform_file_posix.cc (right):
> 
>
https://codereview.chromium.org/22582009/diff/19001/base/platform_file_posix....
> base/platform_file_posix.cc:405: const time_t last_modified_sec =
> file_info.st_mtime;
> should there be a TODO here to investigate the best solution for OS_NACL?

[gavinp, 2013-08-07 18:24:39]

Thanks!

https://codereview.chromium.org/22582009/diff/19001/base/platform_file_posix.cc
File base/platform_file_posix.cc (right):

https://codereview.chromium.org/22582009/diff/19001/base/platform_file_posix....
base/platform_file_posix.cc:405: const time_t last_modified_sec =
file_info.st_mtime;
On 2013/08/07 18:17:28, darin wrote:
> should there be a TODO here to investigate the best solution for OS_NACL?

Done.

[commit-bot: I haz the power, 2013-08-07 21:13:20]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gavinp@chromium.org/22582009/49001

[commit-bot: I haz the power, 2013-08-08 23:12:01]

Change committed as 216478