Glad to see the extensions work being tracked. Are the Chrome-side changes feasible for M67? Chrome OS would like to log UKMs with app IDs/URLs, especially for optimizing the launcher.

Oops, I meant to ask about M66 (this milestone).

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b1f14345786d2b72b682dda6612b20b7ef2b2f88

commit b1f14345786d2b72b682dda6612b20b7ef2b2f88
Author: Brian White <bcwhite@chromium.org>
Date: Thu Mar 01 12:44:15 2018

Allow extension URLs in UKM.

Extensions are covered by a different setting under sync.  If that
setting is enabled then extension:// urls can be included in UKM
information.  This only works if the broader system has consent.

Bug:  810766 
Change-Id: Id0ba274ee4bceafe4521ce1f2f1060533cccc2ac
Reviewed-on: https://chromium-review.googlesource.com/911591
Commit-Queue: Brian White <bcwhite@chromium.org>
Reviewed-by: Bryan McQuade <bmcquade@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Cr-Commit-Position: refs/heads/master@{#540134}
[modify] https://crrev.com/b1f14345786d2b72b682dda6612b20b7ef2b2f88/chrome/browser/metrics/chrome_metrics_service_client.cc
[modify] https://crrev.com/b1f14345786d2b72b682dda6612b20b7ef2b2f88/chrome/browser/metrics/chrome_metrics_service_client.h
[modify] https://crrev.com/b1f14345786d2b72b682dda6612b20b7ef2b2f88/chrome/browser/metrics/chrome_metrics_service_client_unittest.cc
[modify] https://crrev.com/b1f14345786d2b72b682dda6612b20b7ef2b2f88/chrome/browser/metrics/ukm_browsertest.cc
[modify] https://crrev.com/b1f14345786d2b72b682dda6612b20b7ef2b2f88/components/metrics/metrics_service_client.cc
[modify] https://crrev.com/b1f14345786d2b72b682dda6612b20b7ef2b2f88/components/metrics/metrics_service_client.h
[modify] https://crrev.com/b1f14345786d2b72b682dda6612b20b7ef2b2f88/components/metrics_services_manager/metrics_services_manager.cc
[modify] https://crrev.com/b1f14345786d2b72b682dda6612b20b7ef2b2f88/components/ukm/observers/sync_disable_observer.cc
[modify] https://crrev.com/b1f14345786d2b72b682dda6612b20b7ef2b2f88/components/ukm/observers/sync_disable_observer.h
[modify] https://crrev.com/b1f14345786d2b72b682dda6612b20b7ef2b2f88/components/ukm/test_ukm_recorder.cc
[modify] https://crrev.com/b1f14345786d2b72b682dda6612b20b7ef2b2f88/components/ukm/ukm_recorder_impl.cc
[modify] https://crrev.com/b1f14345786d2b72b682dda6612b20b7ef2b2f88/components/ukm/ukm_recorder_impl.h
[modify] https://crrev.com/b1f14345786d2b72b682dda6612b20b7ef2b2f88/components/ukm/ukm_service_unittest.cc
[modify] https://crrev.com/b1f14345786d2b72b682dda6612b20b7ef2b2f88/tools/metrics/histograms/enums.xml

Including the query parameters could be a privacy issue so they should be stripped.

Including the path may be acceptable (needs review by privacy) but there's been no demand for such so far so should also strip those.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c5f347933aad5eb5c282b0016aa76569159dbba0

commit c5f347933aad5eb5c282b0016aa76569159dbba0
Author: Brian White <bcwhite@chromium.org>
Date: Wed Mar 21 13:21:46 2018

Strip path components from extensions URLs.

Bug:  810766 
Change-Id: Ib2804c6218211e75ca2f98d6ddc345740e599d32
Reviewed-on: https://chromium-review.googlesource.com/969406
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Bryan McQuade <bmcquade@chromium.org>
Commit-Queue: Brian White <bcwhite@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544678}
[modify] https://crrev.com/c5f347933aad5eb5c282b0016aa76569159dbba0/components/ukm/ukm_recorder_impl.cc
[modify] https://crrev.com/c5f347933aad5eb5c282b0016aa76569159dbba0/components/ukm/ukm_service_unittest.cc