[Autofill] Introduce autofill/core/common/mojom

This change introduces a new autofill/core/common/mojom folder and moves
enum definitions from autofill_types.mojom there. While this CL doesn't
change any functionality, future CLs will attempt to remove the existing
EnumTraits specializations and directly use the Mojo enums.

Bug: 962853
Change-Id: I9342c6ab39975d8b5ee98b2b3180c50b23f9374e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1610771
Reviewed-by: Mike West <mkwst@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: Fabio Tirelo <ftirelo@chromium.org>
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#661908}
20 files changed