GitLab

Adds PropagateAutofillPredictions method in AutofillHandler, it is
invoked by ContentAutofillDriver, this seems detour, but reasonable
consider AutofillDriver::PropagateAutofillPrediction also applies
to ios.

Adds OnServerPredictionsAvailable to AutofillProvider and test.

Add parameter to enable the autofill download in AutofillHandlerProxy,
the download still disabled.

Bug: 1151542
Change-Id: I2feb36d57f17ee04bd152ce02f493074ba99419d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2574532
Commit-Queue: Michael Bai <michaelbai@chromium.org>
Reviewed-by: Dominic Battré <battre@chromium.org>
Cr-Commit-Position: refs/heads/master@{#834591}