Track size of files serialized by the JsonPrefStore.

Track size of files serialized by the JsonPrefStore.

In an effort to see what percentage of the population has exceedingly large pref files.

BUG=355722
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=283371

[gab, 2014-07-15 04:33:01]

Bernhard/Alexei PTAL.

Thanks!
Gab

[Bernhard Bauer, 2014-07-15 08:09:19]

lgtm

[Alexei Svitkine (slow), 2014-07-15 14:05:50]

https://codereview.chromium.org/391893002/diff/1/tools/metrics/histograms/his...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/391893002/diff/1/tools/metrics/histograms/his...
tools/metrics/histograms/histograms.xml:26961: +    The size of the JSON
settings content about to be written to disk in
The location of histogram doesn't guarantee that the data is written to disk. It
simply serializes to |output|. Wouldn't it make sense to have this histogram in
the caller that calls SerializeData() before writing it to disk?

https://codereview.chromium.org/391893002/diff/1/tools/metrics/histograms/his...
tools/metrics/histograms/histograms.xml:26962: +    kilobytes.
Does this apply to both Local State and Profile Prefs? Please clarify here.

[gab, 2014-07-15 16:43:54]

Augmented the histogram to be even more precise, PTAL.

Thanks!
Gab

https://codereview.chromium.org/391893002/diff/1/tools/metrics/histograms/his...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/391893002/diff/1/tools/metrics/histograms/his...
tools/metrics/histograms/histograms.xml:26961: +    The size of the JSON
settings content about to be written to disk in
On 2014/07/15 14:05:49, Alexei Svitkine wrote:
> The location of histogram doesn't guarantee that the data is written to disk.
It
> simply serializes to |output|. Wouldn't it make sense to have this histogram
in
> the caller that calls SerializeData() before writing it to disk?

The comment says "about to be written to disk", you're technically right there
is a small possibility it doesn't actually make it to disk, but this is not what
we care about, we care about the size of the serialized JSON string.

No we don't want to have this in ImportantFileWriter because that's used by a
lot more things and we want an histogram specific to JSON files (and they're
content's length).

https://codereview.chromium.org/391893002/diff/1/tools/metrics/histograms/his...
tools/metrics/histograms/histograms.xml:26962: +    kilobytes.
On 2014/07/15 14:05:50, Alexei Svitkine wrote:
> Does this apply to both Local State and Profile Prefs? Please clarify here.

Yes, actually added explicit histogram suffixes per JSON file to make the data
easier to analyze (i.e. if we have a bimodal distribution for Preferences, at
least we don't wonder whether that represents the mode for two different files).

[Alexei Svitkine (slow), 2014-07-15 16:49:05]

lgtm

[gab, 2014-07-15 16:54:18]

The CQ bit was checked by gab@chromium.org

[commit-bot: I haz the power, 2014-07-15 16:55:38]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/gab@chromium.org/391893002/20001

[gab, 2014-07-15 21:50:21]

The CQ bit was checked by gab@chromium.org

[commit-bot: I haz the power, 2014-07-15 21:54:43]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/gab@chromium.org/391893002/80001

[commit-bot: I haz the power, 2014-07-16 06:04:48]

Change committed as 283371