Volume click should be marked as default handled

Volume click should be marked as default handled

BUG=

[commit-bot: I haz the power, 2013-05-13 10:43:46]

No reviewers yet.

[eseidel, 2013-05-17 08:10:13]

can we test this?

[calvaris, 2013-05-17 09:55:29]

On 2013/05/17 08:10:13, eseidel wrote:
> can we test this?

This comes from https://bugs.webkit.org/show_bug.cgi?id=112548 . At the moment I
reported it, before the fork, it was a problem in Mac and GTK, but not in
Chromium. I don't know why exactly, but I feel that when the volume bar is
clicked and the volume is finally set, the event should be marked as default
handled even if it doesn't cause a problem now.

What I tried is that this doesn't break any multimedia test in Chromium, and it
doesn't.

[vcarbune.chromium, 2013-05-17 10:16:56]

I think Eric meant to ask if you can add a test to ensure the behavior
happens, not necessarily to illustrate an existing bug.

Maybe you can achieve this through a layout test inspecting the value
of event.defaultPrevented?

[calvaris, 2013-05-17 10:41:57]

On 2013/05/17 10:16:56, vcarbune.chromium wrote:
> I think Eric meant to ask if you can add a test to ensure the behavior
> happens, not necessarily to illustrate an existing bug.
> 
> Maybe you can achieve this through a layout test inspecting the value
> of event.defaultPrevented?

I remember when I was writing the test for WK, that I couldn't find any suitable
check as the event is not defaultPrevented, but default handled and there is no
js binding for that.