[AF] Added browser tests for Autocomplete.

Added the following browser tests for the Autocomplete feature:
Retention Policy Flag ON:
- SubmitSimpleValue_Saves
- SubmitSimpleValue_OTR_DoesNotSave
- SubmitSimpleValue_Disabled_DoesNotSave
- RetentionPolicy_Init_SavesVersionPref
- RetentionPolicy_RemovesExpiredEntry
- RetentionPolicy_DoesNot_RemoveValidEntry

Retention Policy Flag OFF:
- SubmitSimpleValue_Saves
- SubmitSimpleValue_OTR_DoesNotSave
- SubmitSimpleValue_Disabled_DoesNotSave
- RetentionPolicy_DoesNot_RemoveExpiredEntry

Bug: 920620
Change-Id: Id422c68b06938a78e6c12a9011b520e59cc0e021
Reviewed-on: https://chromium-review.googlesource.com/c/1412503
Commit-Queue: Sebastien Lalancette <seblalancette@chromium.org>
Reviewed-by: Fabio Tirelo <ftirelo@chromium.org>
Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#625233}
16 files changed