[AF Wallet] Test histograms for the wallet data bridge

This CL adds histogram checks into unit-tests for the autofill wallet
data bridge. Apart from verifying we send correct metrics, this also
checks that we write to DB only when needed. Since this was previously
untested, this new check revealed a minor typo in one of the tests.

This CL also prepares ground for a follow-up CL that refines wallet
data notifications (i.e. makes the information previously only revealed
to metrics also available to observers).

Bug: 853688
Change-Id: Ia17d54ff81f1d04316c10d6ef548b20e3d8a9905
Reviewed-on: https://chromium-review.googlesource.com/1236275
Commit-Queue: Jan Krcal <jkrcal@chromium.org>
Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593115}
1 file changed