The correct description is to send an authenticated subscription request.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1ef3492242e14636cbf7c5f2bb19097330525c66

commit 1ef3492242e14636cbf7c5f2bb19097330525c66
Author: Mohamed Amir Yosef <mamir@chromium.org>
Date: Mon Jul 17 09:39:08 2017

[NTP::Push] Support Authenticated subscription requests.

Bug:  735465 
Change-Id: I4e1aa8d74be22dd96479f1d5c53e11c89358cfa0
Reviewed-on: https://chromium-review.googlesource.com/562757
Commit-Queue: Mohamed Amir Yosef <mamir@chromium.org>
Reviewed-by: vitaliii <vitaliii@chromium.org>
Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487036}
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/chrome/browser/ntp_snippets/content_suggestions_service_factory.cc
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/BUILD.gn
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/DEPS
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/breaking_news/breaking_news_gcm_app_handler.cc
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/breaking_news/breaking_news_gcm_app_handler.h
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/breaking_news/subscription_json_request.cc
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/breaking_news/subscription_json_request.h
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/breaking_news/subscription_json_request_unittest.cc
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/breaking_news/subscription_manager.cc
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/breaking_news/subscription_manager.h
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/breaking_news/subscription_manager_unittest.cc
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/ntp_snippets_constants.cc
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/ntp_snippets_constants.h
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/pref_names.cc
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/pref_names.h
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/remote/remote_suggestions_fetcher_impl.cc
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/remote/remote_suggestions_fetcher_impl_unittest.cc
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/remote/remote_suggestions_scheduler_impl_unittest.cc
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/remote/remote_suggestions_status_service_unittest.cc
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/remote/test_utils.cc
[modify] https://crrev.com/1ef3492242e14636cbf7c5f2bb19097330525c66/components/ntp_snippets/remote/test_utils.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0c86175a28bce19de3cbf6df8299a80634292593

commit 0c86175a28bce19de3cbf6df8299a80634292593
Author: Mohamed Amir Yosef <mamir@chromium.org>
Date: Mon Jul 17 10:43:52 2017

[NTP::Push] Add API key to the subscription request.

Bug:  735465 
Change-Id: I4810c94f4c5a0f9fd61915affd2a2fd8c7f7e29c
Reviewed-on: https://chromium-review.googlesource.com/570638
Commit-Queue: Mohamed Amir Yosef <mamir@chromium.org>
Reviewed-by: vitaliii <vitaliii@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487039}
[modify] https://crrev.com/0c86175a28bce19de3cbf6df8299a80634292593/chrome/browser/ntp_snippets/content_suggestions_service_factory.cc
[modify] https://crrev.com/0c86175a28bce19de3cbf6df8299a80634292593/components/ntp_snippets/breaking_news/subscription_manager.cc
[modify] https://crrev.com/0c86175a28bce19de3cbf6df8299a80634292593/components/ntp_snippets/breaking_news/subscription_manager.h
[modify] https://crrev.com/0c86175a28bce19de3cbf6df8299a80634292593/components/ntp_snippets/breaking_news/subscription_manager_unittest.cc

Should this still be targeted at M61? Or is this complete?

Complete.