[Password Manager] Ignore empty form names and actions when matching

When matching forms to their PasswordFormManager, we won't use empty
names and empty actions as evidence that two forms are the same.

Bug: 597309
Change-Id: Id568ada643a89c6ec3faa9edacf7d40bcb5bbd16
Reviewed-on: https://chromium-review.googlesource.com/620768
Commit-Queue: Christos Froussios <cfroussios@chromium.org>
Reviewed-by: Maxim Kolosovskiy <kolos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#496263}
3 files changed