Disable scrolling on mousewheel events with ctrl modifier set

Disable scrolling on mousewheel events with ctrl modifier set

Chromium currently swallows all mousewheel events with the ctrl modifier set (for zooming) instead of sending them to the renderer.  I plan to change this to align with Firefox and IE - send the event first, and if it goes unhandled then invoke browser zoom.  See http://crbug.com/289887 and the linked chromium-dev thread for discussion.

In order to do that I need to ensure ctrl+wheel events don't trigger scrolling by default.  EventHandler::handleWheelEvent already has an early-out for the ctrl modifier case, but it's not enough since the default wheel handler has already been run.  This changes adds an identical early-out to EventHandler::defaultWheelEventHandler.

Test depends on EventSender change here: http://crrev.com/253923

BUG=289887
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=168088

[Rick Byers, 2014-02-27 18:01:25]

Ian,
Are you comfortable reviewing this tiny scrolling-related change?  I'll have to
wait for the EventSender change to land in chromium (otherwise the new test will
fail), but since this patch is itself blocking addition work on the chromium
side I'd like to pipeline them up.

Thanks,
   Rick

[Rick Byers, 2014-02-27 23:44:19]

On 2014/02/27 18:01:25, Rick Byers wrote:
> Ian,
> Are you comfortable reviewing this tiny scrolling-related change?  

Rob, Ian would prefer we get someone familiar with blink events to review before
he does an OWNERs review.  Can you please take a look?  It's trivial (related to
the maps pinch/wheel issue we discussed).

> I'll have to
> wait for the EventSender change to land in chromium (otherwise the new test
will
> fail), but since this patch is itself blocking addition work on the chromium
> side I'd like to pipeline them up.

Chromium side has now landed, verifying tests pass on the bots...

> 
> Thanks,
>    Rick

[rjkroege, 2014-02-28 00:54:02]

lgtm

[Ian Vollick, 2014-02-28 00:59:44]

On 2014/02/28 00:54:02, rjkroege wrote:
> lgtm

rslgtm

[Rick Byers, 2014-02-28 01:00:50]

The CQ bit was checked by rbyers@chromium.org

[Rick Byers, 2014-02-28 01:01:19]

On 2014/02/28 00:59:44, Ian Vollick wrote:
> On 2014/02/28 00:54:02, rjkroege wrote:
> > lgtm
> 
> rslgtm

Thanks for the quick review guys!

[commit-bot: I haz the power, 2014-02-28 01:13:01]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/rbyers@chromium.org/183403002/1

[commit-bot: I haz the power, 2014-02-28 02:54:51]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-02-28 02:54:52]

Retried try job too often on win_blink_rel for step(s) webkit_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_blink_...

[Ian Vollick, 2014-02-28 04:00:25]

The CQ bit was checked by vollick@chromium.org

[commit-bot: I haz the power, 2014-02-28 04:00:43]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/rbyers@chromium.org/183403002/1

[commit-bot: I haz the power, 2014-02-28 08:13:04]

Change committed as 168088