The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/bdf9cc17d8963a3e8ca3cc3965e683ca9f8d9f58

commit bdf9cc17d8963a3e8ca3cc3965e683ca9f8d9f58
Author: Daniel Murphy <dmurph@chromium.org>
Date: Wed Dec 05 22:29:38 2018

[IndexedDB] Remove transaction support from observers in content/.

Observers will no longer have transaction support, due to inherent
locking it causes and how this conflicts with lifecycle work. It also
complicates roll out of LevelDBScopes integration with IndexedDB.

Note this doesn't remove the existence of transactions in IDB Observer
code in blink/. This will be done in the next CL.

R=cmp@chromium.org

Bug: 903509, 903515
Change-Id: I215842e9f80baa37eda43cc43426c3c747df5c3a
Reviewed-on: https://chromium-review.googlesource.com/c/1327722
Commit-Queue: Daniel Murphy <dmurph@chromium.org>
Reviewed-by: Chase Phillips <cmp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#614135}
[modify] https://crrev.com/bdf9cc17d8963a3e8ca3cc3965e683ca9f8d9f58/content/browser/indexed_db/indexed_db_connection.cc
[modify] https://crrev.com/bdf9cc17d8963a3e8ca3cc3965e683ca9f8d9f58/content/browser/indexed_db/indexed_db_connection.h
[modify] https://crrev.com/bdf9cc17d8963a3e8ca3cc3965e683ca9f8d9f58/content/browser/indexed_db/indexed_db_database.cc
[modify] https://crrev.com/bdf9cc17d8963a3e8ca3cc3965e683ca9f8d9f58/content/browser/indexed_db/indexed_db_transaction.cc
[modify] https://crrev.com/bdf9cc17d8963a3e8ca3cc3965e683ca9f8d9f58/content/browser/indexed_db/indexed_db_transaction.h
[modify] https://crrev.com/bdf9cc17d8963a3e8ca3cc3965e683ca9f8d9f58/content/browser/indexed_db/indexed_db_transaction_coordinator.cc
[modify] https://crrev.com/bdf9cc17d8963a3e8ca3cc3965e683ca9f8d9f58/content/browser/indexed_db/indexed_db_transaction_coordinator.h
[delete] https://crrev.com/d560b578390fb80b01229e8db64a878eb7e8dfb8/third_party/blink/web_tests/storage/indexeddb/observer-transaction-test.html
[modify] https://crrev.com/bdf9cc17d8963a3e8ca3cc3965e683ca9f8d9f58/third_party/blink/web_tests/storage/indexeddb/resources/observer-tests.js

observer transactions still need to be removed from on the blink side now (and in the mojo bindings.

dmurph@: Is this still P1?