The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1bf626176bbc98086f163286b83eea916e97f1ac

commit 1bf626176bbc98086f163286b83eea916e97f1ac
Author: Rayan Kanso <rayankans@chromium.org>
Date: Mon Dec 10 13:00:44 2018

[Background Fetch] Support multiple delegate clients.

Creating a download job (registering a fetch) should include which
client to communicate the changes to.

This also has the added benefit that client logic can be moved out of
the delegate proxy and into the job controller.

Bug:  907075 
Change-Id: I3daba90b3ea148c66980ba7cb61d0bd7dc0fd8b9
Reviewed-on: https://chromium-review.googlesource.com/c/1346029
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Commit-Queue: Rayan Kanso <rayankans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615100}
[modify] https://crrev.com/1bf626176bbc98086f163286b83eea916e97f1ac/chrome/browser/background_fetch/background_fetch_delegate_impl.cc
[modify] https://crrev.com/1bf626176bbc98086f163286b83eea916e97f1ac/chrome/browser/background_fetch/background_fetch_delegate_impl.h
[modify] https://crrev.com/1bf626176bbc98086f163286b83eea916e97f1ac/content/browser/background_fetch/background_fetch_context.cc
[modify] https://crrev.com/1bf626176bbc98086f163286b83eea916e97f1ac/content/browser/background_fetch/background_fetch_delegate_proxy.cc
[modify] https://crrev.com/1bf626176bbc98086f163286b83eea916e97f1ac/content/browser/background_fetch/background_fetch_delegate_proxy.h
[modify] https://crrev.com/1bf626176bbc98086f163286b83eea916e97f1ac/content/browser/background_fetch/background_fetch_delegate_proxy_unittest.cc
[modify] https://crrev.com/1bf626176bbc98086f163286b83eea916e97f1ac/content/browser/background_fetch/background_fetch_job_controller_unittest.cc
[modify] https://crrev.com/1bf626176bbc98086f163286b83eea916e97f1ac/content/browser/background_fetch/background_fetch_scheduler_unittest.cc
[modify] https://crrev.com/1bf626176bbc98086f163286b83eea916e97f1ac/content/browser/background_fetch/mock_background_fetch_delegate.cc
[modify] https://crrev.com/1bf626176bbc98086f163286b83eea916e97f1ac/content/browser/background_fetch/mock_background_fetch_delegate.h
[modify] https://crrev.com/1bf626176bbc98086f163286b83eea916e97f1ac/content/public/browser/background_fetch_delegate.cc
[modify] https://crrev.com/1bf626176bbc98086f163286b83eea916e97f1ac/content/public/browser/background_fetch_delegate.h
[modify] https://crrev.com/1bf626176bbc98086f163286b83eea916e97f1ac/content/shell/browser/web_test/web_test_background_fetch_delegate.cc
[modify] https://crrev.com/1bf626176bbc98086f163286b83eea916e97f1ac/content/shell/browser/web_test/web_test_background_fetch_delegate.h