[Autofill] Class to track the state of an ongoing profile import process

This CL introduces a class that is used to track the process of an
ongoing profile import from a form submission that involves user
interactions.

Change-Id: I2d34968b97ad6448a578ebb10098903e54f7f6b3
Bug: 1175693
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2810641
Commit-Queue: Matthias Körber <koerber@google.com>
Reviewed-by: Christoph Schwering <schwering@google.com>
Cr-Commit-Position: refs/heads/master@{#872865}