PasswordAutofillAgent: only check visibility if needed

PasswordAutofillAgent: only check visibility if needed

PasswordAutofillAgent::SendPasswordForms is called twice during page load:
On DidFinishDocumentLoad, when it is interested in parsed HTML forms,
and on DidFinishLoad, when it is interested in those forms, which are also visible.

Currently, the method does the visibility check all the times, and throuws out the result in the first situation.

This is not only wasting computational resources, but possibly causing crashes due to not finished rendering computations.

This CL fixes that, and only does the visibility check if needed.

BUG=457243
Committed: https://crrev.com/ae130ef602aef780ed69597eb875dca2d904d473
Cr-Commit-Position: refs/heads/master@{#316218}

[vabr (Chromium), 2015-02-13 13:50:52]

vabr@chromium.org changed reviewers:
+ mkwst@chromium.org

[vabr (Chromium), 2015-02-13 13:50:53]

Hi Mike!

Would you review another small CL for me please?

Cheers,
Vaclav

[Mike West, 2015-02-13 13:57:35]

LGTM.

[vabr (Chromium), 2015-02-13 14:04:10]

The CQ bit was checked by vabr@chromium.org

[commit-bot: I haz the power, 2015-02-13 14:04:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/925983002/1

[commit-bot: I haz the power, 2015-02-13 15:14:41]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-13 15:15:43]

Patchset 1 (id:??) landed as
https://crrev.com/ae130ef602aef780ed69597eb875dca2d904d473
Cr-Commit-Position: refs/heads/master@{#316218}