Add UMA to collect latency numbers for the Data Reduction Proxy secure proxy check.

Add UMA to collect latency numbers for the Data Reduction Proxy secure proxy check.

BUG=486897
Committed: https://crrev.com/e544d83bc7fe0ecd8f7a99593715a09862e7bf1a
Cr-Commit-Position: refs/heads/master@{#329906}

[jeremyim, 2015-05-11 20:54:34]

jeremyim@chromium.org changed reviewers:
+ asvitkine@google.com, bengr@chromium.org

[jeremyim, 2015-05-11 20:54:34]

PTAL. Thanks!

bengr => components/data_reduction_proxy/*
asvitkine => histograms.xml

[bengr, 2015-05-11 21:46:37]

https://codereview.chromium.org/1132413003/diff/1/components/data_reduction_p...
File components/data_reduction_proxy/core/browser/data_reduction_proxy_config.cc
(right):

https://codereview.chromium.org/1132413003/diff/1/components/data_reduction_p...
components/data_reduction_proxy/core/browser/data_reduction_proxy_config.cc:72:
base::Time::Now() - secure_proxy_check_start_time_;
Is secure_proxy_check_start_time_ guaranteed to be before Now()?

[jeremyim, 2015-05-11 22:09:16]

jeremyim@chromium.org changed reviewers:
+ asvitkine@chromium.org
- asvitkine@google.com

[jeremyim, 2015-05-11 22:09:16]

https://codereview.chromium.org/1132413003/diff/1/components/data_reduction_p...
File components/data_reduction_proxy/core/browser/data_reduction_proxy_config.cc
(right):

https://codereview.chromium.org/1132413003/diff/1/components/data_reduction_p...
components/data_reduction_proxy/core/browser/data_reduction_proxy_config.cc:72:
base::Time::Now() - secure_proxy_check_start_time_;
On 2015/05/11 21:46:37, bengr wrote:
> Is secure_proxy_check_start_time_ guaranteed to be before Now()?

As long as the user doesn't change the wall clock during the start end end of
the secure proxy check, then yes.

[bengr, 2015-05-13 17:52:40]

https://codereview.chromium.org/1132413003/diff/1/components/data_reduction_p...
File components/data_reduction_proxy/core/browser/data_reduction_proxy_config.cc
(right):

https://codereview.chromium.org/1132413003/diff/1/components/data_reduction_p...
components/data_reduction_proxy/core/browser/data_reduction_proxy_config.cc:72:
base::Time::Now() - secure_proxy_check_start_time_;
On 2015/05/11 22:09:16, jeremyim wrote:
> On 2015/05/11 21:46:37, bengr wrote:
> > Is secure_proxy_check_start_time_ guaranteed to be before Now()?
> 
> As long as the user doesn't change the wall clock during the start end end of
> the secure proxy check, then yes.

Then it isn't guaranteed. Might be worth discarding negative values, or setting
them to zero.

[jeremyim, 2015-05-13 18:24:06]

https://codereview.chromium.org/1132413003/diff/1/components/data_reduction_p...
File components/data_reduction_proxy/core/browser/data_reduction_proxy_config.cc
(right):

https://codereview.chromium.org/1132413003/diff/1/components/data_reduction_p...
components/data_reduction_proxy/core/browser/data_reduction_proxy_config.cc:72:
base::Time::Now() - secure_proxy_check_start_time_;
On 2015/05/13 17:52:39, bengr wrote:
> On 2015/05/11 22:09:16, jeremyim wrote:
> > On 2015/05/11 21:46:37, bengr wrote:
> > > Is secure_proxy_check_start_time_ guaranteed to be before Now()?
> > 
> > As long as the user doesn't change the wall clock during the start end end
of
> > the secure proxy check, then yes.
> 
> Then it isn't guaranteed. Might be worth discarding negative values, or
setting
> them to zero.

Done.

[bengr, 2015-05-14 15:54:11]

https://codereview.chromium.org/1132413003/diff/20001/components/data_reducti...
File components/data_reduction_proxy/core/browser/data_reduction_proxy_config.cc
(right):

https://codereview.chromium.org/1132413003/diff/20001/components/data_reducti...
components/data_reduction_proxy/core/browser/data_reduction_proxy_config.cc:73:
if (secure_proxy_check_latency > base::TimeDelta()) {
Suggest >= jic we have 0 values.

[jeremyim, 2015-05-14 15:58:06]

https://codereview.chromium.org/1132413003/diff/20001/components/data_reducti...
File components/data_reduction_proxy/core/browser/data_reduction_proxy_config.cc
(right):

https://codereview.chromium.org/1132413003/diff/20001/components/data_reducti...
components/data_reduction_proxy/core/browser/data_reduction_proxy_config.cc:73:
if (secure_proxy_check_latency > base::TimeDelta()) {
On 2015/05/14 15:54:11, bengr wrote:
> Suggest >= jic we have 0 values.

Done.

[Alexei Svitkine (slow), 2015-05-14 16:55:19]

lgtm

[bengr, 2015-05-14 18:25:47]

lgtm

[jeremyim, 2015-05-14 18:33:57]

The CQ bit was checked by jeremyim@chromium.org

[commit-bot: I haz the power, 2015-05-14 18:36:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1132413003/40001

[commit-bot: I haz the power, 2015-05-14 19:46:04]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-05-14 19:47:46]

Patchset 3 (id:??) landed as
https://crrev.com/e544d83bc7fe0ecd8f7a99593715a09862e7bf1a
Cr-Commit-Position: refs/heads/master@{#329906}