Merge-72 [AF] Add SyncState suffix to some key autofill metrics.

The suffixes describing the sync state are:
SignedOut
SignedIn
kSignedInAndWalletSyncTransportEnabled
SignedInAndSyncFeature

The metrics that will have those suffixes are
Autofill.FormEvents
Autofill.IsEnabled.PageLoad
Autofill.SaveCreditCardPrompt

The previous histograms will continue to be logged. This is only
additional logging.

TBR=sebsg@chromium.org

(cherry picked from commit 119a2fe85a3ae98d60d9e5a5b0837c20cb21bfb3)

Bug: 903290
Change-Id: Ibc96a1db12408f13d40fe75ed9aec96af80eac96
Reviewed-on: https://chromium-review.googlesource.com/c/1326602
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Reviewed-by: Jesse Doherty <jwd@chromium.org>
Reviewed-by: Fabio Tirelo <ftirelo@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#614517}
Reviewed-on: https://chromium-review.googlesource.com/c/1369630
Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/branch-heads/3626@{#196}
Cr-Branched-From: d897fb137fbaaa9355c0c93124cc048824eb1e65-refs/heads/master@{#612437}
18 files changed