Autofill: Fix WalletIntegrationAvailable() regression.

Autofill: Fix WalletIntegrationAvailable() regression.

Accidentally inverted a check during refactoring in
https://crrev.com/1137513002

Add back the '!' character that I deleted, and add unit tests to
guard against future regressions.

BUG=486675
Committed: https://crrev.com/93d1d2484b1637bb7a69eade2cdd398b216bdc69
Cr-Commit-Position: refs/heads/master@{#329933}

[bondd, 2015-05-13 01:32:01]

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

[bondd, 2015-05-13 01:32:01]

bondd@chromium.org changed required reviewers:
+ estade@chromium.org

[Evan Stade, 2015-05-13 21:53:12]

wow these are some thorough tests! lgtm

[Evan Stade, 2015-05-13 21:53:15]

The CQ bit was checked by estade@chromium.org

[commit-bot: I haz the power, 2015-05-13 21:54:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1138373002/1

[commit-bot: I haz the power, 2015-05-13 22:24:58]

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

[commit-bot: I haz the power, 2015-05-13 22:24:59]

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

[bondd, 2015-05-14 20:27:52]

The CQ bit was checked by bondd@chromium.org

[bondd, 2015-05-14 20:27:52]

The patchset sent to the CQ was uploaded after l-g-t-m from estade@chromium.org
Link to the patchset: https://codereview.chromium.org/1138373002/#ps20001
(title: "Add missing dep for GN build.")

[commit-bot: I haz the power, 2015-05-14 20:28:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1138373002/20001

[commit-bot: I haz the power, 2015-05-14 21:21:42]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-05-14 21:22:17]

Patchset 2 (id:??) landed as
https://crrev.com/93d1d2484b1637bb7a69eade2cdd398b216bdc69
Cr-Commit-Position: refs/heads/master@{#329933}