The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/668dd31af63e75b47c1fa4908836755fbfc907de

commit 668dd31af63e75b47c1fa4908836755fbfc907de
Author: Tanja Gornak <melandory@chromium.org>
Date: Thu Jul 26 11:01:39 2018

Implement unsubscription request.

This CL adds an ability to unsubscribe from topic via
PerUserTopicRegistrationRequest.

Bug:  867402 , 801985
Change-Id: Ie6a43d66a938480b2f047e3dee12803ba10ea40e
Reviewed-on: https://chromium-review.googlesource.com/1150039
Reviewed-by: Pavel Yatsuk <pavely@chromium.org>
Reviewed-by: Jan Krcal <jkrcal@chromium.org>
Commit-Queue: Tatiana Gornak <melandory@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578256}
[modify] https://crrev.com/668dd31af63e75b47c1fa4908836755fbfc907de/components/invalidation/impl/per_user_topic_registration_manager.cc
[modify] https://crrev.com/668dd31af63e75b47c1fa4908836755fbfc907de/components/invalidation/impl/per_user_topic_registration_request.cc
[modify] https://crrev.com/668dd31af63e75b47c1fa4908836755fbfc907de/components/invalidation/impl/per_user_topic_registration_request.h
[modify] https://crrev.com/668dd31af63e75b47c1fa4908836755fbfc907de/components/invalidation/impl/per_user_topic_registration_request_unittest.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/704397d3b39f870067ab7fcc1ea28a651b706a1a

commit 704397d3b39f870067ab7fcc1ea28a651b706a1a
Author: Tanja Gornak <melandory@chromium.org>
Date: Fri Aug 17 08:21:35 2018

Serialize and deserialize InvalidationObjectId.

This CL implements routines for serializing and deserializing object
ids, which simplifies the logic for storing topics which were already
registered for.

TBR: pavely@chromium.org
Bug:  867402 , 801985
Change-Id: Ie859cc87b8e9b3cff54ae2af0eeed68467af09af
Reviewed-on: https://chromium-review.googlesource.com/1154921
Reviewed-by: Pavel Yatsuk <pavely@chromium.org>
Reviewed-by: Cait Phillips <caitkp@chromium.org>
Reviewed-by: Jan Krcal <jkrcal@chromium.org>
Commit-Queue: Tatiana Gornak <melandory@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583991}
[modify] https://crrev.com/704397d3b39f870067ab7fcc1ea28a651b706a1a/components/BUILD.gn
[modify] https://crrev.com/704397d3b39f870067ab7fcc1ea28a651b706a1a/components/invalidation/impl/per_user_topic_registration_manager.cc
[modify] https://crrev.com/704397d3b39f870067ab7fcc1ea28a651b706a1a/components/invalidation/impl/per_user_topic_registration_manager_unittest.cc
[modify] https://crrev.com/704397d3b39f870067ab7fcc1ea28a651b706a1a/components/invalidation/public/BUILD.gn
[modify] https://crrev.com/704397d3b39f870067ab7fcc1ea28a651b706a1a/components/invalidation/public/invalidation_util.cc
[modify] https://crrev.com/704397d3b39f870067ab7fcc1ea28a651b706a1a/components/invalidation/public/invalidation_util.h
[add] https://crrev.com/704397d3b39f870067ab7fcc1ea28a651b706a1a/components/invalidation/public/invalidation_util_unittest.cc