Implement TOGGLE_EXPANSION action for the ARC notifications.

Implement TOGGLE_EXPANSION action for the ARC notifications.

TOGGLE_EXPANSION action will be triggerred when a user triggers
DO_DEFAULT accessibility action on the notification.

I use the target of the mouse pressing event on
ArcCustomNotificationView to distinguish accessibility DO_DEFAULT
action and normal click on the notification.
This hack will be removed after making |AXActionData| be propagated to
|HandleAccessibleAction|.

BUG=703989
Review-Url: https://codereview.chromium.org/2767253005
Cr-Commit-Position: refs/heads/master@{#460087}
(cherry picked from commit b7af49bce7ecd2e79c8a54712d27bd45e27c2420)

Review-Url: https://codereview.chromium.org/2793853002 .
Cr-Commit-Position: refs/branch-heads/3029@{#538}
Cr-Branched-From: 939b32ee5ba05c396eef3fd992822fcca9a2e262-refs/heads/master@{#454471}
Committed: https://chromium.googlesource.com/chromium/src/+/03873abfe51c7da3dd502d3addd309c1c1a74697

[yhanada, 2017-04-03 02:02:00]

Description was changed from

==========
Implement TOGGLE_EXPANSION action for the ARC notifications.

TOGGLE_EXPANSION action will be triggerred when a user triggers
DO_DEFAULT accessibility action on the notification.

I use the target of the mouse pressing event on
ArcCustomNotificationView to distinguish accessibility DO_DEFAULT
action and normal click on the notification.
This hack will be removed after making |AXActionData| be propagated to
|HandleAccessibleAction|.

BUG=703989

Review-Url: https://codereview.chromium.org/2767253005
Cr-Commit-Position: refs/heads/master@{#460087}
(cherry picked from commit b7af49bce7ecd2e79c8a54712d27bd45e27c2420)
==========

to

==========
Implement TOGGLE_EXPANSION action for the ARC notifications.

TOGGLE_EXPANSION action will be triggerred when a user triggers
DO_DEFAULT accessibility action on the notification.

I use the target of the mouse pressing event on
ArcCustomNotificationView to distinguish accessibility DO_DEFAULT
action and normal click on the notification.
This hack will be removed after making |AXActionData| be propagated to
|HandleAccessibleAction|.

BUG=703989

Review-Url: https://codereview.chromium.org/2767253005
Cr-Commit-Position: refs/heads/master@{#460087}
(cherry picked from commit b7af49bce7ecd2e79c8a54712d27bd45e27c2420)

Review-Url: https://codereview.chromium.org/2793853002 .
Cr-Commit-Position: refs/branch-heads/3029@{#538}
Cr-Branched-From:
939b32ee5ba05c396eef3fd992822fcca9a2e262-refs/heads/master@{#454471}
Committed:
https://chromium.googlesource.com/chromium/src/+/03873abfe51c7da3dd502d3addd3...
==========

[yhanada, 2017-04-03 02:02:02]

Committed patchset #1 (id:1) manually as
03873abfe51c7da3dd502d3addd309c1c1a74697.