Implement support for <audio> in ChromeVox Next.

Implement support for <audio> in ChromeVox Next.

- pick up the decsription attribute in buttons
- add the help attribute in sliders

TEST=chromevox_tests --gtest_filter=OutputE2ETest.Audio

Committed: https://crrev.com/8be28877e6d5072d77dab0488e4198abd00c482e
Cr-Commit-Position: refs/heads/master@{#326841}

[David Tseng, 2015-04-22 23:14:31]

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

[dmazzoni, 2015-04-24 13:41:07]

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

[dmazzoni, 2015-04-24 13:41:08]

lgtm

https://codereview.chromium.org/1099023005/diff/20001/chrome/browser/resource...
File chrome/browser/resources/chromeos/chromevox/cvox2/background/output.js
(right):

https://codereview.chromium.org/1099023005/diff/20001/chrome/browser/resource...
chrome/browser/resources/chromeos/chromevox/cvox2/background/output.js:166:
speak: '$name $value $description $role',
As suggested in the other CL, how about:

$name $description $help $value $ole

...and do this to all rules where we have $name now. Then when we have the new
name calc available we can just replace with $name only.

[David Tseng, 2015-04-24 16:13:20]

On 2015/04/24 13:41:08, dmazzoni wrote:
> lgtm
> 
>
https://codereview.chromium.org/1099023005/diff/20001/chrome/browser/resource...
> File chrome/browser/resources/chromeos/chromevox/cvox2/background/output.js
> (right):
> 
>
https://codereview.chromium.org/1099023005/diff/20001/chrome/browser/resource...
> chrome/browser/resources/chromeos/chromevox/cvox2/background/output.js:166:
> speak: '$name $value $description $role',
> As suggested in the other CL, how about:
> 
> $name $description $help $value $ole
> 
> ...and do this to all rules where we have $name now. Then when we have the new
> name calc available we can just replace with $name only.

Yup; sounds good. I'll move $description to the default rule and merge this cl
to pick up $help in the input type cl.

[David Tseng, 2015-04-24 17:41:19]

The CQ bit was checked by dtseng@chromium.org

[David Tseng, 2015-04-24 17:41:20]

The patchset sent to the CQ was uploaded after l-g-t-m from
dmazzoni@chromium.org
Link to the patchset: https://codereview.chromium.org/1099023005/#ps60001
(title: "Rebase")

[commit-bot: I haz the power, 2015-04-24 17:42:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1099023005/60001

[commit-bot: I haz the power, 2015-04-24 18:14:40]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-04-24 18:16:15]

Patchset 4 (id:??) landed as
https://crrev.com/8be28877e6d5072d77dab0488e4198abd00c482e
Cr-Commit-Position: refs/heads/master@{#326841}