Move password filling logic into components.

Note: Unit test will be added in https://chromium-review.googlesource.com/c/chromium/src/+/1195292.

Bug: 865114
Cq-Include-Trybots: luci.chromium.try:ios-simulator-cronet;luci.chromium.try:ios-simulator-full-configs
Change-Id: I91e187ae90b7515cc3bc37cdd80bdfbf33ae5ca1
Reviewed-on: https://chromium-review.googlesource.com/1195246
Commit-Queue: Scott Wu <scottwu@chromium.org>
Reviewed-by: Vasilii Sukhanov <vasilii@chromium.org>
Reviewed-by: John Wu <jzw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#587986}
3 files changed