The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ac8c4b0f02699304e2021e3420e1343ebdaf6e38

commit ac8c4b0f02699304e2021e3420e1343ebdaf6e38
Author: Alexey Baskakov <loyso@chromium.org>
Date: Wed Nov 07 06:10:02 2018

WebApp: Introduce WebAppDatabase.

For now we try to reuse as much USS code as possible.
It has limitations and drawbacks (see the code).

We will rethink our persistence code later when we start to design
WebAppSyncBridge
(an implementation for syncer::ModelTypeSyncBridge interface).

Bug:  896150 
Change-Id: Ia898b905f39869a6b1c3f79751358425449a617a
Reviewed-on: https://chromium-review.googlesource.com/c/1295529
Reviewed-by: calamity <calamity@chromium.org>
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Reviewed-by: Ben Wells <benwells@chromium.org>
Commit-Queue: Alexey Baskakov <loyso@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605974}
[modify] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/BUILD.gn
[add] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/abstract_web_app_database.h
[add] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/proto/BUILD.gn
[add] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/proto/web_app.proto
[add] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/test/test_web_app_database.cc
[add] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/test/test_web_app_database.h
[add] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/test/test_web_app_database_factory.cc
[add] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/test/test_web_app_database_factory.h
[add] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/web_app_database.cc
[add] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/web_app_database.h
[add] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/web_app_database_factory.cc
[add] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/web_app_database_factory.h
[add] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/web_app_database_unittest.cc
[modify] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/web_app_install_manager_unittest.cc
[modify] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/web_app_provider.cc
[modify] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/web_app_provider.h
[modify] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/web_app_registrar.cc
[modify] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/web_app_registrar.h
[modify] https://crrev.com/ac8c4b0f02699304e2021e3420e1343ebdaf6e38/chrome/browser/web_applications/web_app_registrar_unittest.cc