[Password Manager] Relax matching for username overrides.

[Password Manager] Relax matching for username overrides.

Currently if the form changes in any way between parsing and form submission
any server overrides for the form will be ignored. Relax the matching to only
take into account name and action for the form and name for the field. This
is similar to how Autofill matches.

BUG=476092
Committed: https://crrev.com/2c03ed4ed9b71cd79380a6df7641c1da74dd04fd
Cr-Commit-Position: refs/heads/master@{#325380}

[Garrett Casto, 2015-04-15 00:19:21]

The CQ bit was checked by gcasto@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-04-15 00:19:39]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1088973003/1

[Garrett Casto, 2015-04-15 00:19:49]

gcasto@chromium.org changed reviewers:
+ dvadym@chromium.org

[commit-bot: I haz the power, 2015-04-15 00:31:11]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-04-15 00:31:12]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[dvadym, 2015-04-15 12:01:09]

LGTM

[Garrett Casto, 2015-04-16 01:01:10]

The CQ bit was checked by gcasto@chromium.org

[commit-bot: I haz the power, 2015-04-16 01:01:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1088973003/1

[commit-bot: I haz the power, 2015-04-16 02:32:46]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-16 02:33:42]

Patchset 1 (id:??) landed as
https://crrev.com/2c03ed4ed9b71cd79380a6df7641c1da74dd04fd
Cr-Commit-Position: refs/heads/master@{#325380}