IndexedDB: Remove content/common/indexed_db/

- Remove unused var kNoDatabaseId
- Port constants to Mojo file
- Update WATCHLISTS to remove old paths / add new paths

Bug: 717812
Change-Id: I706d4df3c38cbc95b68d59fefa3632d9e1438f13
Reviewed-on: https://chromium-review.googlesource.com/1194877
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Victor Costan <pwnall@chromium.org>
Commit-Queue: Chase Phillips <cmp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#587643}
12 files changed