Drive-by comment. You might consider setting up a Chirp alert for this which would automatically alert if this metric changed.

rch: yes, we'll definitely do that, thanks.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b2288ecde37cbe28ac295607f8686906f1c618e8

commit b2288ecde37cbe28ac295607f8686906f1c618e8
Author: estark <estark@chromium.org>
Date: Thu Mar 31 21:45:01 2016

Add error callback to net::CertificateReportSender

We want to start recording UMA metrics (and perhaps eventually taking
other actions such as retrying) when various types of certificate
reports fail to send. This CL adds an error callback to the
net::CertificateReportSender class to allow us to do this.

It also fixes a small bug where apparently we were printing a log
message about reports failing to send even when they succeeded.

BUG= 596624 

Review URL: https://codereview.chromium.org/1847563004

Cr-Commit-Position: refs/heads/master@{#384402}

[modify] https://crrev.com/b2288ecde37cbe28ac295607f8686906f1c618e8/net/url_request/certificate_report_sender.cc
[modify] https://crrev.com/b2288ecde37cbe28ac295607f8686906f1c618e8/net/url_request/certificate_report_sender.h
[modify] https://crrev.com/b2288ecde37cbe28ac295607f8686906f1c618e8/net/url_request/certificate_report_sender_unittest.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f2979127c4951011a74f00fab8fdff94d87952de

commit f2979127c4951011a74f00fab8fdff94d87952de
Author: estark <estark@chromium.org>
Date: Tue Apr 05 17:04:39 2016

Use CertificateReportSender error callback to record HPKP UMA metrics

This CL does two things:
1. Use the CertificateReportSender error callback to record UMA metrics
when we fail to send an HPKP report.
2. The error callback argument of a URLRequest* wasn't set up quite
right to do this; TransportSecurityState provides the callback, but
TransportSecurityState is in net/http and shouldn't depend on
URLRequest. So instead I changed the callback arguments to be the report
URI and the net error from sending the report.

BUG= 596624 

Review URL: https://codereview.chromium.org/1850853004

Cr-Commit-Position: refs/heads/master@{#385198}

[modify] https://crrev.com/f2979127c4951011a74f00fab8fdff94d87952de/net/http/transport_security_state.cc
[modify] https://crrev.com/f2979127c4951011a74f00fab8fdff94d87952de/net/http/transport_security_state.h
[modify] https://crrev.com/f2979127c4951011a74f00fab8fdff94d87952de/net/http/transport_security_state_unittest.cc
[modify] https://crrev.com/f2979127c4951011a74f00fab8fdff94d87952de/net/url_request/certificate_report_sender.cc
[modify] https://crrev.com/f2979127c4951011a74f00fab8fdff94d87952de/net/url_request/certificate_report_sender.h
[modify] https://crrev.com/f2979127c4951011a74f00fab8fdff94d87952de/net/url_request/certificate_report_sender_unittest.cc
[modify] https://crrev.com/f2979127c4951011a74f00fab8fdff94d87952de/net/url_request/url_request_unittest.cc
[modify] https://crrev.com/f2979127c4951011a74f00fab8fdff94d87952de/tools/metrics/histograms/histograms.xml

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8e872d46c8951a7a8333a9883e6c8bd79b154d34

commit 8e872d46c8951a7a8333a9883e6c8bd79b154d34
Author: estark <estark@chromium.org>
Date: Thu Apr 07 23:10:04 2016

Add UMA metric for Expect CT failure

When an Expect CT report fails to send, record a UMA histogram with the
net error code.

BUG= 596624 

Review URL: https://codereview.chromium.org/1866203003

Cr-Commit-Position: refs/heads/master@{#385915}

[modify] https://crrev.com/8e872d46c8951a7a8333a9883e6c8bd79b154d34/chrome/browser/ssl/chrome_expect_ct_reporter.cc
[modify] https://crrev.com/8e872d46c8951a7a8333a9883e6c8bd79b154d34/chrome/browser/ssl/chrome_expect_ct_reporter_unittest.cc
[modify] https://crrev.com/8e872d46c8951a7a8333a9883e6c8bd79b154d34/tools/metrics/histograms/histograms.xml

It looks like two CLs have landed, can we close this bug now?

Not quite, we still need UMA for Safe Browsing certificate report failures. (Basically, passing an ErrorCallback here: https://cs.chromium.org/chromium/src/components/certificate_reporting/error_reporter.cc?sq=package:chromium&dr=CSs&rcl=1467300303&l=112)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a79bbb7b735bfbc7b84518bdd6f166a2fb39f7c1

commit a79bbb7b735bfbc7b84518bdd6f166a2fb39f7c1
Author: estark <estark@chromium.org>
Date: Wed Jul 20 17:43:28 2016

Fix up certificate error reporting histograms

This CL adds a failure histogram for certificate error reporting,
similar to the histograms we have for Expect CT and HPKP reports.

It also negates the net error codes for Expect CT and HPKP histograms,
to match up with the histogram enums. (See  bug 616599 .)

BUG= 616599 , 596624 

Review-Url: https://codereview.chromium.org/2120683002
Cr-Commit-Position: refs/heads/master@{#406604}

[modify] https://crrev.com/a79bbb7b735bfbc7b84518bdd6f166a2fb39f7c1/chrome/browser/ssl/chrome_expect_ct_reporter.cc
[modify] https://crrev.com/a79bbb7b735bfbc7b84518bdd6f166a2fb39f7c1/chrome/browser/ssl/chrome_expect_ct_reporter_unittest.cc
[modify] https://crrev.com/a79bbb7b735bfbc7b84518bdd6f166a2fb39f7c1/components/BUILD.gn
[modify] https://crrev.com/a79bbb7b735bfbc7b84518bdd6f166a2fb39f7c1/components/certificate_reporting/BUILD.gn
[modify] https://crrev.com/a79bbb7b735bfbc7b84518bdd6f166a2fb39f7c1/components/certificate_reporting/DEPS
[modify] https://crrev.com/a79bbb7b735bfbc7b84518bdd6f166a2fb39f7c1/components/certificate_reporting/error_reporter.cc
[modify] https://crrev.com/a79bbb7b735bfbc7b84518bdd6f166a2fb39f7c1/components/certificate_reporting/error_reporter_unittest.cc
[modify] https://crrev.com/a79bbb7b735bfbc7b84518bdd6f166a2fb39f7c1/components/components_tests.gyp
[modify] https://crrev.com/a79bbb7b735bfbc7b84518bdd6f166a2fb39f7c1/ios/chrome/browser/BUILD.gn
[modify] https://crrev.com/a79bbb7b735bfbc7b84518bdd6f166a2fb39f7c1/ios/chrome/browser/DEPS
[modify] https://crrev.com/a79bbb7b735bfbc7b84518bdd6f166a2fb39f7c1/ios/chrome/browser/ssl/ios_ssl_blocking_page.h
[modify] https://crrev.com/a79bbb7b735bfbc7b84518bdd6f166a2fb39f7c1/ios/chrome/ios_chrome.gyp
[modify] https://crrev.com/a79bbb7b735bfbc7b84518bdd6f166a2fb39f7c1/net/http/transport_security_state.cc
[modify] https://crrev.com/a79bbb7b735bfbc7b84518bdd6f166a2fb39f7c1/net/http/transport_security_state_unittest.cc
[modify] https://crrev.com/a79bbb7b735bfbc7b84518bdd6f166a2fb39f7c1/tools/metrics/histograms/histograms.xml

Security>UX component is deprecated in favor of the Team-Security-UX label