The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6b4648285ac8e8640309e6405646fa3fc4862ed8

commit 6b4648285ac8e8640309e6405646fa3fc4862ed8
Author: Josh Karlin <jkarlin@chromium.org>
Date: Fri Nov 02 19:20:33 2018

[BackgroundSync] Remove Registration.id which is unused

At one point we identified sync registrations by an id instead of by
the tag. But we've long since only used the tag. Remove the id.

Bug:  901034 
Change-Id: I94eb60fb51e9e036c98dff78c6fc8cd2f190232d
Reviewed-on: https://chromium-review.googlesource.com/c/1313190
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Commit-Queue: Josh Karlin <jkarlin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605010}
[modify] https://crrev.com/6b4648285ac8e8640309e6405646fa3fc4862ed8/content/browser/background_sync/background_sync.proto
[modify] https://crrev.com/6b4648285ac8e8640309e6405646fa3fc4862ed8/content/browser/background_sync/background_sync_manager.cc
[modify] https://crrev.com/6b4648285ac8e8640309e6405646fa3fc4862ed8/content/browser/background_sync/background_sync_manager.h
[modify] https://crrev.com/6b4648285ac8e8640309e6405646fa3fc4862ed8/content/browser/background_sync/background_sync_manager_unittest.cc
[modify] https://crrev.com/6b4648285ac8e8640309e6405646fa3fc4862ed8/content/browser/background_sync/background_sync_registration.cc
[modify] https://crrev.com/6b4648285ac8e8640309e6405646fa3fc4862ed8/content/browser/background_sync/background_sync_registration.h
[modify] https://crrev.com/6b4648285ac8e8640309e6405646fa3fc4862ed8/content/browser/background_sync/background_sync_service_impl.cc
[modify] https://crrev.com/6b4648285ac8e8640309e6405646fa3fc4862ed8/third_party/blink/public/platform/modules/background_sync/background_sync.mojom
[modify] https://crrev.com/6b4648285ac8e8640309e6405646fa3fc4862ed8/third_party/blink/renderer/modules/background_sync/sync_manager.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f6033c7dc8b700c1579d224324e46825a0faed29

commit f6033c7dc8b700c1579d224324e46825a0faed29
Author: Josh Karlin <jkarlin@chromium.org>
Date: Mon Nov 05 20:42:15 2018

[BackgroundSync] Remove the requested network state from registration

We used to support sync registrations having various types of network
conditions under which they would fire. That's not specced and it's
unused, so removing it.

Bug:  901034 
Change-Id: I38fb1cf2779aebe8814f7bb1bf5564f467397149
Reviewed-on: https://chromium-review.googlesource.com/c/1313191
Commit-Queue: Josh Karlin <jkarlin@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605448}
[modify] https://crrev.com/f6033c7dc8b700c1579d224324e46825a0faed29/content/browser/background_sync/background_sync.proto
[modify] https://crrev.com/f6033c7dc8b700c1579d224324e46825a0faed29/content/browser/background_sync/background_sync_manager.cc
[modify] https://crrev.com/f6033c7dc8b700c1579d224324e46825a0faed29/content/browser/background_sync/background_sync_manager_unittest.cc
[modify] https://crrev.com/f6033c7dc8b700c1579d224324e46825a0faed29/content/browser/background_sync/background_sync_network_observer.cc
[modify] https://crrev.com/f6033c7dc8b700c1579d224324e46825a0faed29/content/browser/background_sync/background_sync_network_observer.h
[modify] https://crrev.com/f6033c7dc8b700c1579d224324e46825a0faed29/content/browser/background_sync/background_sync_network_observer_unittest.cc
[modify] https://crrev.com/f6033c7dc8b700c1579d224324e46825a0faed29/content/browser/background_sync/background_sync_registration_options.cc
[modify] https://crrev.com/f6033c7dc8b700c1579d224324e46825a0faed29/content/browser/background_sync/background_sync_registration_options.h
[modify] https://crrev.com/f6033c7dc8b700c1579d224324e46825a0faed29/content/browser/background_sync/background_sync_service_impl.cc
[modify] https://crrev.com/f6033c7dc8b700c1579d224324e46825a0faed29/third_party/blink/public/platform/modules/background_sync/background_sync.mojom
[modify] https://crrev.com/f6033c7dc8b700c1579d224324e46825a0faed29/third_party/blink/renderer/modules/background_sync/sync_manager.cc