ARIA state/property aria-pressed is not exposed(Blink).

ARIA state/property aria-pressed is not exposed(Blink).

According to specs http://rawgit.com/w3c/aria/master/core-aam/core-aam.html

aria-pressed {true, mixed} should set STATE_SYSTEM_PRESSED and false should
clear STATE_SYSTEM_PRESSED

HTML:
<div tabindex=0 role="button">Regular button</div>
<div tabindex=1 role="button" aria-pressed="false">Toggle button unpressed</div>
<div tabindex=2 role="button" aria-pressed="true">Toggle button pressed</div>
<div tabindex=3 role="button" aria-pressed="mixed">Toggle button mixed</div>

AX Tree
    ROLE_SYSTEM_PUSHBUTTON FOCUSABLE
    IA2_ROLE_TOGGLE_BUTTON FOCUSABLE checkable:true
    IA2_ROLE_TOGGLE_BUTTON PRESSED FOCUSABLE checkable:true
    IA2_ROLE_TOGGLE_BUTTON PRESSED FOCUSABLE checkable:true

BUG=171625
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=186789

[shreeramk, 2014-12-01 10:29:05]

shreeram.k@samsung.com changed reviewers:
+ dmazzoni@chromium.org

[shreeramk, 2014-12-01 10:29:06]

Please review.

Thanks!!

[shreeramk, 2014-12-05 04:52:16]

On 2014/12/01 10:29:06, shreeramk wrote:
> Please review.
> 
> Thanks!!

@Dmazzoni: Could you please take a look?
Thanks!

[shreeramk, 2014-12-08 19:37:30]

@Dominic: Please take a look. Thanks!!

[dmazzoni, 2014-12-09 17:03:32]

The CQ bit was checked by dmazzoni@chromium.org

[dmazzoni, 2014-12-09 17:03:32]

lgtm

[commit-bot: I haz the power, 2014-12-09 17:03:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/767183002/1

[commit-bot: I haz the power, 2014-12-09 17:42:08]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=186789