Added LeastUsedAccountDays metric

Added LeastUsedAccountDays metric

BUG=204944
NOTRY=true

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=221686

[Denis Kuznetsov (DE-MUC), 2013-08-28 17:38:30]

Related changes in ChromeOS :
https://chromium-review.googlesource.com/#/c/167340/

[Alexei Svitkine (slow), 2013-08-28 17:41:21]

https://chromiumcodereview.appspot.com/23462008/diff/1/tools/metrics/histogra...
File tools/metrics/histograms/histograms.xml (right):

https://chromiumcodereview.appspot.com/23462008/diff/1/tools/metrics/histogra...
tools/metrics/histograms/histograms.xml:10366: 
Nit: Add units="days"

https://chromiumcodereview.appspot.com/23462008/diff/1/tools/metrics/histogra...
tools/metrics/histograms/histograms.xml:10367: 
Nit: Mention when this is sampled (periodically every X amount of time, on
startup, etc?).

[Denis Kuznetsov (DE-MUC), 2013-08-29 07:56:31]

On 2013/08/28 17:41:21, Alexei Svitkine wrote:
>
https://chromiumcodereview.appspot.com/23462008/diff/1/tools/metrics/histogra...
> File tools/metrics/histograms/histograms.xml (right):
> 
>
https://chromiumcodereview.appspot.com/23462008/diff/1/tools/metrics/histogra...
> tools/metrics/histograms/histograms.xml:10366: 
> Nit: Add units="days"
> 
>
https://chromiumcodereview.appspot.com/23462008/diff/1/tools/metrics/histogra...
> tools/metrics/histograms/histograms.xml:10367: 
> Nit: Mention when this is sampled (periodically every X amount of time, on
> startup, etc?).

Done.

[Alexei Svitkine (slow), 2013-08-29 14:32:52]

LGTM

[Denis Kuznetsov (DE-MUC), 2013-08-30 15:18:54]

On 2013/08/29 14:32:52, Alexei Svitkine wrote:
> LGTM

Please take a look on updated version.

[Alexei Svitkine (slow), 2013-08-30 15:41:05]

https://chromiumcodereview.appspot.com/23462008/diff/15001/tools/metrics/hist...
File tools/metrics/histograms/histograms.xml (right):

https://chromiumcodereview.appspot.com/23462008/diff/15001/tools/metrics/hist...
tools/metrics/histograms/histograms.xml:5184: +    Chrome OS histogram that
keeps track of th days since the least frequently
Nit: "th" -> "the"

https://chromiumcodereview.appspot.com/23462008/diff/15001/tools/metrics/hist...
tools/metrics/histograms/histograms.xml:10438: +<histogram
name="Platform.DiskUsage.LeastUsedAccountDays" units="days">
Hmm, looking at this again, I don't get why this is under Platform.DiskUsage.
Could you explain the difference between this and Login.LeastUsedAccountDays?

[Denis Kuznetsov (DE-MUC), 2013-08-30 16:42:35]

https://chromiumcodereview.appspot.com/23462008/diff/15001/tools/metrics/hist...
File tools/metrics/histograms/histograms.xml (right):

https://chromiumcodereview.appspot.com/23462008/diff/15001/tools/metrics/hist...
tools/metrics/histograms/histograms.xml:5184: +    Chrome OS histogram that
keeps track of th days since the least frequently
On 2013/08/30 15:41:05, Alexei Svitkine wrote:
> Nit: "th" -> "the"

Done.

https://chromiumcodereview.appspot.com/23462008/diff/15001/tools/metrics/hist...
tools/metrics/histograms/histograms.xml:10438: +<histogram
name="Platform.DiskUsage.LeastUsedAccountDays" units="days">
On 2013/08/30 15:41:05, Alexei Svitkine wrote:
> Hmm, looking at this again, I don't get why this is under Platform.DiskUsage.
> Could you explain the difference between this and Login.LeastUsedAccountDays?

Second one is reported every boot / 24h, and we need it to gauge the user impact
of the auto deletion feature (see issue).

First one is reported only when device is low on the disk space (<1GB free), and
actual metric is split by number of user on device. We need this metric to
estimate how we should adjust algorithms for automatic cleanup.

[Alexei Svitkine (slow), 2013-08-30 16:50:36]

On 2013/08/30 16:42:35, Denis Kuznetsov wrote:
> First one is reported only when device is low on the disk space (<1GB free)

Aha, that's the bit I was missing. Can you add this to the histogram
description? Thanks!

[Denis Kuznetsov (DE-MUC), 2013-08-30 17:21:56]

On 2013/08/30 16:50:36, Alexei Svitkine wrote:
> On 2013/08/30 16:42:35, Denis Kuznetsov wrote:
> > First one is reported only when device is low on the disk space (<1GB free)
> 
> Aha, that's the bit I was missing. Can you add this to the histogram
> description? Thanks!

Done.

[Alexei Svitkine (slow), 2013-08-30 17:24:51]

lgtm

[commit-bot: I haz the power, 2013-09-06 11:59:07]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/antrim@chromium.org/23462008/23001

[commit-bot: I haz the power, 2013-09-06 11:59:34]

Change committed as 221686