Autofill: Consider placeholder text when inferring an input's label.

Autofill: Consider placeholder text when inferring an input's label.

This fixes Staples checkout.

BUG=426571
Committed: https://crrev.com/86db401f0fba9d6f708fbfb72e38d97e3fe042e1
Cr-Commit-Position: refs/heads/master@{#301189}

[Evan Stade, 2014-10-23 22:19:37]

estade@chromium.org changed reviewers:
+ isherman@chromium.org

[Evan Stade, 2014-10-23 22:19:37]

somewhat surprised this doesn't affect the rest of the test suite at all

[Ilya Sherman, 2014-10-23 22:27:21]

Hmm, I wonder whether we should treat the placeholder text as a label, or
include it separately in the FormFieldData struct.  I guess we can start with
this, and update to include the data as a separate field if need be.  LGTM.

FWIW, most sites simulate placeholder text rather than using the HTML5
attribute, which is probably why this doesn't affect the rest of the test suite
much.

[Evan Stade, 2014-10-24 18:36:29]

The CQ bit was checked by estade@chromium.org

[commit-bot: I haz the power, 2014-10-24 18:37:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/675883002/40001

[commit-bot: I haz the power, 2014-10-24 20:33:34]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2014-10-24 20:34:10]

Patchset 3 (id:??) landed as
https://crrev.com/86db401f0fba9d6f708fbfb72e38d97e3fe042e1
Cr-Commit-Position: refs/heads/master@{#301189}