Fix webstore extension reading in views.

Fix webstore extension reading in views.

Reading of views is now handled using ChromeVox Next with the automation API. The current Next background page fails on non-CROS because there's no commands block. We get an error like
getAll called on undefined.

(chrome.commands is undefined).

TEST=manually build ChromeVox; verify views reads properly.

Committed: https://crrev.com/6cd3b230c3b280a037efb2db8048e4cda4f69fbc
Cr-Commit-Position: refs/heads/master@{#330249}

[David Tseng, 2015-05-15 20:04:03]

dtseng@chromium.org changed reviewers:
+ dmazzoni@chromium.org

[dmazzoni, 2015-05-15 23:50:50]

The CQ bit was checked by dmazzoni@chromium.org

[dmazzoni, 2015-05-15 23:50:50]

lgtm

[commit-bot: I haz the power, 2015-05-15 23:51:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1138773006/20001

[commit-bot: I haz the power, 2015-05-16 00:36:45]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-05-18 11:29:58]

Patchset 2 (id:??) landed as
https://crrev.com/6cd3b230c3b280a037efb2db8048e4cda4f69fbc
Cr-Commit-Position: refs/heads/master@{#330249}