Ah yes, I removed use of it when fixing blob reading to no longer use URLRequest, but then forgot to follow up with more cleanup.

Thanks for the context!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/181717f7abd2da06bf332654776144ea564cd3fa

commit 181717f7abd2da06bf332654776144ea564cd3fa
Author: Matt Menke <mmenke@chromium.org>
Date: Tue Oct 09 16:18:06 2018

[IndexedDB]: Remove unused URLRequestContextGetters.

https://chromium-review.googlesource.com/1164523 made IndexedDB no
longer use its URLRequestContextGetter parameter, but didn't remove the
parameter. This CL just removes the unused parameter, as
URLRequestContextGetter should no longer be used in the browser process.

Bug:  893299 
Change-Id: I179354c9c3dd1baef1cbf0b1e834fed54204b302
Reviewed-on: https://chromium-review.googlesource.com/c/1269555
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Daniel Murphy <dmurph@chromium.org>
Commit-Queue: Daniel Murphy <dmurph@chromium.org>
Commit-Queue: Matt Menke <mmenke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#597937}
[modify] https://crrev.com/181717f7abd2da06bf332654776144ea564cd3fa/content/browser/indexed_db/indexed_db_backing_store.cc
[modify] https://crrev.com/181717f7abd2da06bf332654776144ea564cd3fa/content/browser/indexed_db/indexed_db_backing_store.h
[modify] https://crrev.com/181717f7abd2da06bf332654776144ea564cd3fa/content/browser/indexed_db/indexed_db_backing_store_unittest.cc
[modify] https://crrev.com/181717f7abd2da06bf332654776144ea564cd3fa/content/browser/indexed_db/indexed_db_cleanup_on_io_error_unittest.cc
[modify] https://crrev.com/181717f7abd2da06bf332654776144ea564cd3fa/content/browser/indexed_db/indexed_db_dispatcher_host.cc
[modify] https://crrev.com/181717f7abd2da06bf332654776144ea564cd3fa/content/browser/indexed_db/indexed_db_dispatcher_host.h
[modify] https://crrev.com/181717f7abd2da06bf332654776144ea564cd3fa/content/browser/indexed_db/indexed_db_dispatcher_host_unittest.cc
[modify] https://crrev.com/181717f7abd2da06bf332654776144ea564cd3fa/content/browser/indexed_db/indexed_db_factory.h
[modify] https://crrev.com/181717f7abd2da06bf332654776144ea564cd3fa/content/browser/indexed_db/indexed_db_factory_impl.cc
[modify] https://crrev.com/181717f7abd2da06bf332654776144ea564cd3fa/content/browser/indexed_db/indexed_db_factory_impl.h
[modify] https://crrev.com/181717f7abd2da06bf332654776144ea564cd3fa/content/browser/indexed_db/indexed_db_factory_unittest.cc
[modify] https://crrev.com/181717f7abd2da06bf332654776144ea564cd3fa/content/browser/indexed_db/indexed_db_fake_backing_store.cc
[modify] https://crrev.com/181717f7abd2da06bf332654776144ea564cd3fa/content/browser/indexed_db/indexed_db_unittest.cc
[modify] https://crrev.com/181717f7abd2da06bf332654776144ea564cd3fa/content/browser/indexed_db/mock_indexed_db_factory.h
[modify] https://crrev.com/181717f7abd2da06bf332654776144ea564cd3fa/content/browser/renderer_host/render_process_host_impl.cc