The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/539ace770a1288275c1c3450239aa6d01b6da908

commit 539ace770a1288275c1c3450239aa6d01b6da908
Author: Tanja Gornak <melandory@chromium.org>
Date: Thu Jul 19 15:42:18 2018

FCM Network handler for the invalidations.

The network handler purpose is:

1. Connect to the GCM channel
2. Retrieve the instance_id token and forward it to the registration manager.
3. Forward incoming messages to the message handlers.

Bug:  863893 , 801985
Change-Id: I236e5a2374468aaceb69641b05d535a3685d716e
Reviewed-on: https://chromium-review.googlesource.com/1138317
Commit-Queue: Tatiana Gornak <melandory@chromium.org>
Reviewed-by: Pavel Yatsuk <pavely@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576506}
[modify] https://crrev.com/539ace770a1288275c1c3450239aa6d01b6da908/components/invalidation/impl/BUILD.gn
[add] https://crrev.com/539ace770a1288275c1c3450239aa6d01b6da908/components/invalidation/impl/fcm_network_handler.cc
[add] https://crrev.com/539ace770a1288275c1c3450239aa6d01b6da908/components/invalidation/impl/fcm_network_handler.h
[add] https://crrev.com/539ace770a1288275c1c3450239aa6d01b6da908/components/invalidation/impl/fcm_network_handler_unittests.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7002a7d32567a76f67e5eebe34a17bd0e653ba3c

commit 7002a7d32567a76f67e5eebe34a17bd0e653ba3c
Author: Tanja Gornak <melandory@chromium.org>
Date: Fri Jul 20 10:19:49 2018

PerUserTopicregistrationManager doesn't require instance_id in ctor

Ditch the instance_id from ctor of the PerUserTopicRegistrationManager.

Bug:  863893 , 801985
Change-Id: Ia2b459bfa9e8f556230461f7e211c005e1c38e26
Reviewed-on: https://chromium-review.googlesource.com/1143395
Reviewed-by: Pavel Yatsuk <pavely@chromium.org>
Commit-Queue: Tatiana Gornak <melandory@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576827}
[modify] https://crrev.com/7002a7d32567a76f67e5eebe34a17bd0e653ba3c/components/invalidation/impl/fcm_sync_invalidation_listener_unittest.cc
[modify] https://crrev.com/7002a7d32567a76f67e5eebe34a17bd0e653ba3c/components/invalidation/impl/per_user_topic_registration_manager.cc
[modify] https://crrev.com/7002a7d32567a76f67e5eebe34a17bd0e653ba3c/components/invalidation/impl/per_user_topic_registration_manager.h
[modify] https://crrev.com/7002a7d32567a76f67e5eebe34a17bd0e653ba3c/components/invalidation/impl/per_user_topic_registration_manager_unittest.cc