Use totmaps if available on chromeos

Use totmaps if available on chromeos

We currently use statm on linux. This provides less than great results. 
We take total resident memory and subtract "shared pages" from it instead of
using a count of pages that only this process has mapped.

On chromeos we've added totmaps which sums up the fields from the process'
smaps.

BUG=125150
TEST=Examine memory reports from about:memory and task manager, and compare
     them to the sums of the results in the smaps.

R=thestig@chromium.org, willchan@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=202639

[willchan no longer on Chromium, 2013-05-27 21:01:45]

Sending to erg/thestig for review. Happy to rubberstamp.

[Lei Zhang, 2013-05-28 03:37:40]

lgtm

https://codereview.chromium.org/15779007/diff/2001/base/process/process_metri...
File base/process/process_metrics_linux.cc (right):

https://codereview.chromium.org/15779007/diff/2001/base/process/process_metri...
base/process/process_metrics_linux.cc:296:
DCHECK_EQ(totmaps_fields[kPssIndex-1], "Pss:");
nit: prefer DCHECK_EQ(expected, actual)

https://codereview.chromium.org/15779007/diff/2001/base/process/process_metri...
base/process/process_metrics_linux.cc:301:
base::StringToInt(totmaps_fields[kPssIndex], &pss);
nit: already in namespace base, no need for base::

https://codereview.chromium.org/15779007/diff/2001/base/process/process_metri...
base/process/process_metrics_linux.cc:301:
base::StringToInt(totmaps_fields[kPssIndex], &pss);
StringToInt() can fail - check return result.

GetWorkingSetKBytesStatm() has the same problem, but that's probably my fault.

[willchan no longer on Chromium, 2013-05-28 03:57:13]

rubberstamp lgtm


On Mon, May 27, 2013 at 8:37 PM, <thestig@chromium.org> wrote:

> lgtm
>
>
>
>
> https://codereview.chromium.**org/15779007/diff/2001/base/**
>
process/process_metrics_linux.**cc<https://codereview.chromium.org/15779007/diff/2001/base/process/process_metrics_linux.cc>
> File base/process/process_metrics_**linux.cc (right):
>
> https://codereview.chromium.**org/15779007/diff/2001/base/**
>
process/process_metrics_linux.**cc#newcode296<https://codereview.chromium.org/15779007/diff/2001/base/process/process_metrics_linux.cc#newcode296>
> base/process/process_metrics_**linux.cc:296:
> DCHECK_EQ(totmaps_fields[**kPssIndex-1], "Pss:");
> nit: prefer DCHECK_EQ(expected, actual)
>
> https://codereview.chromium.**org/15779007/diff/2001/base/**
>
process/process_metrics_linux.**cc#newcode301<https://codereview.chromium.org/15779007/diff/2001/base/process/process_metrics_linux.cc#newcode301>
> base/process/process_metrics_**linux.cc:301:
> base::StringToInt(totmaps_**fields[kPssIndex], &pss);
> nit: already in namespace base, no need for base::
>
> https://codereview.chromium.**org/15779007/diff/2001/base/**
>
process/process_metrics_linux.**cc#newcode301<https://codereview.chromium.org/15779007/diff/2001/base/process/process_metrics_linux.cc#newcode301>
> base/process/process_metrics_**linux.cc:301:
> base::StringToInt(totmaps_**fields[kPssIndex], &pss);
> StringToInt() can fail - check return result.
>
> GetWorkingSetKBytesStatm() has the same problem, but that's probably my
> fault.
>
>
https://codereview.chromium.**org/15779007/<https://codereview.chromium.org/1...
>

[DaveMoore, 2013-05-28 20:16:56]

Committed patchset #3 manually as r202639.