https://crrev.com/c/937710

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/686f65606344681ade1981559738160e877e3a7d

commit 686f65606344681ade1981559738160e877e3a7d
Author: Marc Treib <treib@chromium.org>
Date: Thu Mar 01 11:13:23 2018

Wallet Sync: Add metrics for added/removed cards and addresses

This adds UMA histograms to record the number of Wallet credit cards
and addresses that were added and removed during each Sync cycle (i.e.
during startup, and whenever we receive an update from the server).

Bug:  816831 
Change-Id: I6673e1737f79dea9669b3a96f0ae9164645ea8da
Reviewed-on: https://chromium-review.googlesource.com/937710
Commit-Queue: Marc Treib <treib@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#540125}
[modify] https://crrev.com/686f65606344681ade1981559738160e877e3a7d/components/autofill/core/browser/webdata/autofill_wallet_syncable_service.cc
[modify] https://crrev.com/686f65606344681ade1981559738160e877e3a7d/components/autofill/core/browser/webdata/autofill_wallet_syncable_service.h
[modify] https://crrev.com/686f65606344681ade1981559738160e877e3a7d/components/autofill/core/browser/webdata/autofill_wallet_syncable_service_unittest.cc
[modify] https://crrev.com/686f65606344681ade1981559738160e877e3a7d/tools/metrics/histograms/histograms.xml