The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/40c4389f9e84668cf2c6052a0a34350080c308ec

commit 40c4389f9e84668cf2c6052a0a34350080c308ec
Author: Miriam Gershenson <mgersh@chromium.org>
Date: Thu Sep 28 15:24:27 2017

DNS histogram cleanup, part 1

Some of the DNS histograms are not useful anymore. A lot of them
have no data but were never marked as obsolete. This CL deletes the ones
I don't intend to replace with anything. Rearranging of the remaining
metrics to be more useful will come in a future CL.

Bug:  769320 
Change-Id: Ia45aaa5034371aa7780145ea991f624b52dd3b1a
Reviewed-on: https://chromium-review.googlesource.com/673264
Reviewed-by: Julia Tuttle <juliatuttle@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Miriam Gershenson <mgersh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#505030}
[modify] https://crrev.com/40c4389f9e84668cf2c6052a0a34350080c308ec/chrome/browser/net/url_info.cc
[modify] https://crrev.com/40c4389f9e84668cf2c6052a0a34350080c308ec/net/dns/dns_config_service_posix.cc
[modify] https://crrev.com/40c4389f9e84668cf2c6052a0a34350080c308ec/net/dns/dns_config_service_win.cc
[modify] https://crrev.com/40c4389f9e84668cf2c6052a0a34350080c308ec/net/dns/dns_session.cc
[modify] https://crrev.com/40c4389f9e84668cf2c6052a0a34350080c308ec/net/dns/host_resolver_impl.cc
[modify] https://crrev.com/40c4389f9e84668cf2c6052a0a34350080c308ec/tools/metrics/histograms/histograms.xml

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/90d05e08a3f97289971e1d54f488287a42e3942b

commit 90d05e08a3f97289971e1d54f488287a42e3942b
Author: Miriam Gershenson <mgersh@chromium.org>
Date: Thu Sep 28 19:29:28 2017

DNS histogram cleanup, part 2

This CL merges the higher-level DNS histograms to include both async and
system resolver timing in the same metrics. This will allow easier use
in Finch experiments. It also adds the new Net.DNS.TotalTimeNotCached
histogram, which is equivalent to Net.DNS.TotalTime minus cached and
other synchronous resolutions, for better alerts. The current TotalTime
histogram is hard to use for alerts because the median is 0.

Bug:  769320 
Change-Id: Iea7873ddd284fffe1e0e414f1e33f2e07053c0ca
Reviewed-on: https://chromium-review.googlesource.com/673092
Commit-Queue: Miriam Gershenson <mgersh@chromium.org>
Reviewed-by: Julia Tuttle <juliatuttle@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#505119}
[modify] https://crrev.com/90d05e08a3f97289971e1d54f488287a42e3942b/net/dns/host_resolver_impl.cc
[modify] https://crrev.com/90d05e08a3f97289971e1d54f488287a42e3942b/tools/metrics/histograms/histograms.xml

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6160466523bb411e66ab80a880ff05a248381d9c

commit 6160466523bb411e66ab80a880ff05a248381d9c
Author: Miriam Gershenson <mgersh@chromium.org>
Date: Thu Sep 28 23:51:11 2017

DNS histogram cleanup, part 3

This CL removes all the old DNS.Resolve* and AsyncDNS.Resolve*
histograms and replaces them with a new set. The new Net.DNS.Resolve*
histograms measure timing and success/failure at the Job layer, and each
type of Task gets its own set to measure Task layer timing and
success/failure.

Bug:  769320 
Change-Id: I0b0df897310a474fd11022f932724c8d40789090
Reviewed-on: https://chromium-review.googlesource.com/687836
Commit-Queue: Miriam Gershenson <mgersh@chromium.org>
Reviewed-by: Julia Tuttle <juliatuttle@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#505215}
[modify] https://crrev.com/6160466523bb411e66ab80a880ff05a248381d9c/net/dns/host_resolver_impl.cc
[modify] https://crrev.com/6160466523bb411e66ab80a880ff05a248381d9c/tools/metrics/histograms/histograms.xml

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/aaf139580bc8d4e6816e358ea22674967485bc30

commit aaf139580bc8d4e6816e358ea22674967485bc30
Author: Miriam Gershenson <mgersh@chromium.org>
Date: Mon Nov 27 16:06:06 2017

Add histograms for DNS error codes

DNS failure is very common, and there is currently no tracking of
overall failure causes. Histograms are separated by how fast the failure
happened because there's a large clump of almost immediate failures that
I want to investigate further, and causes are probably different between
the two categories. 10 ms was chosen as the cutoff point by looking at
the Net.DNS.ResolveFailureTime histogram.

Bug:  769320 
Change-Id: I15fa7105d2208d47799935141faf3b118b52e0b2
Reviewed-on: https://chromium-review.googlesource.com/782662
Reviewed-by: Steven Holte <holte@chromium.org>
Reviewed-by: Julia Tuttle <juliatuttle@chromium.org>
Commit-Queue: Miriam Gershenson <mgersh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#519312}
[modify] https://crrev.com/aaf139580bc8d4e6816e358ea22674967485bc30/net/dns/host_resolver_impl.cc
[modify] https://crrev.com/aaf139580bc8d4e6816e358ea22674967485bc30/tools/metrics/histograms/histograms.xml

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/19faef8176944732b29b2e2c2d2c25f594a8c3d4

commit 19faef8176944732b29b2e2c2d2c25f594a8c3d4
Author: Miriam Gershenson <mgersh@chromium.org>
Date: Wed Feb 07 23:56:44 2018

Add histogram to track all DnsTask errors

There is already a histogram to track DnsTask errors that are followed
by a ProcTask success, and a pair of histograms that track overall error
codes for the host resolver. Overall error codes always come from the
system resolver because of the fallback, and these error codes aren't
very descriptive. Tracking DnsTask errors will give a better picture of
error causes.

Bug:  769320 
Change-Id: I40259169417168031cf31dda1c65d48e5636c4f7
Reviewed-on: https://chromium-review.googlesource.com/905262
Reviewed-by: Steven Holte <holte@chromium.org>
Reviewed-by: Julia Tuttle <juliatuttle@chromium.org>
Commit-Queue: Miriam Gershenson <mgersh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#535195}
[modify] https://crrev.com/19faef8176944732b29b2e2c2d2c25f594a8c3d4/net/dns/host_resolver_impl.cc
[modify] https://crrev.com/19faef8176944732b29b2e2c2d2c25f594a8c3d4/tools/metrics/histograms/histograms.xml

I didn't do everything in the original doc, but I think I'm going to leave it as it is now because the rest is just unnecessary churn. Marking this fixed.