Add POINTER_WHEEL_CHANGED event to mojo.

Add POINTER_WHEEL_CHANGED event to mojo.

Also creating a MouseWheelEvent instead of a MouseEvent
from PointerEvent if its type is POINTER_WHEEL_CHANGED
to avoid stack overflow.

BUG=642486
TEST=events_unittests + manual

Committed: https://crrev.com/ec96963b90a87eb8e30dd9e8b74f5951eeda14f2
Cr-Commit-Position: refs/heads/master@{#416072}

[riajiang, 2016-08-31 18:50:14]

Description was changed from

==========
Add POINTER_WHEEL_CHANGED event to mojo.

BUG=642486
TEST=events_unittests
==========

to

==========
Add POINTER_WHEEL_CHANGED event to mojo.

Also creating a MouseWheelEvent instead of a MouseEvent
from PointerEvent if its type is POINTER_WHEEL_CHANGED 
to avoid stack overflow.

BUG=642486
TEST=events_unittests
==========

[riajiang, 2016-08-31 18:50:14]

riajiang@chromium.org changed reviewers:
+ sadrul@chromium.org, sky@chromium.org, tsepez@chromium.org

[riajiang, 2016-08-31 19:01:51]

tsepez@, could you take a look at ui/events/mojo?
sadrul@, could you take a look at ui/events?
sky@, could you take a look at ash and services/ui?
Thanks!

[sky, 2016-08-31 20:24:27]

LGTM

[Tom Sepez, 2016-08-31 22:01:20]

lgtm

[sadrul, 2016-09-01 05:38:55]

https://codereview.chromium.org/2301593002/diff/1/ui/events/event.cc
File ui/events/event.cc (right):

https://codereview.chromium.org/2301593002/diff/1/ui/events/event.cc#newcode501
ui/events/event.cc:501: SetType(ET_MOUSEWHEEL);
Can you change this to a NOTREACHED()?

[Peter Kasting, 2016-09-01 07:26:01]

This is a super-bikeshed so please do not block on me.  I happened to notice
this driving by and had some possible food for thought.

It makes sense for a lot of things to say "pointer" instead of "mouse" to cover
e.g. trackpads.  But it there a type of a wheel event that isn't a mouse wheel? 
I thought only mice had wheels?

I partly ask because I'm a Grammar Nazi -- technically, "pointer" refers to the
cursor that is moved rather than the device doing the moving, so saying e.g.
"pointer move event" makes sense, but "pointer wheel event" doesn't, because a
pointer cannot have a wheel -- and partly because I worry about whether handling
code.

* Should code be able to safely assume a POINTER_WHEEL_EVENT is a mouse event? 
I don't think the code you've written does so, but might someone in the future?
* If not, then should code be able to assume that non-mouse POINTER_WHEEL_EVENTs
do not need special handling as mouse POINTER_WHEEL_EVENTs do?  This is an
assumption the code looks to make today; is it tested?  Can we ever generate or
handle such non-mouse POINTER_WHEEL_EVENTs?

If, OTOH, something is a MOUSE_WHEEL_EVENT, all these become clear.

That's all :)

[riajiang, 2016-09-01 15:29:21]

https://codereview.chromium.org/2301593002/diff/1/ui/events/event.cc
File ui/events/event.cc (right):

https://codereview.chromium.org/2301593002/diff/1/ui/events/event.cc#newcode501
ui/events/event.cc:501: SetType(ET_MOUSEWHEEL);
On 2016/09/01 05:38:54, sadrul wrote:
> Can you change this to a NOTREACHED()?

As discussed, changing it to not set type here. Also changing some DCHECKs.

[sadrul, 2016-09-01 19:54:24]

lgtm

[riajiang, 2016-09-01 20:20:57]

The CQ bit was checked by riajiang@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-09-01 20:21:49]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-09-01 21:33:15]

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

[commit-bot: I haz the power, 2016-09-01 21:33:16]

Dry run: This issue passed the CQ dry run.

[riajiang, 2016-09-01 21:45:31]

The CQ bit was checked by riajiang@chromium.org

[riajiang, 2016-09-01 21:45:31]

The patchset sent to the CQ was uploaded after l-g-t-m from tsepez@chromium.org,
sky@chromium.org, sadrul@chromium.org
Link to the patchset: https://codereview.chromium.org/2301593002/#ps40001
(title: "rebase")

[commit-bot: I haz the power, 2016-09-01 21:46:04]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-09-01 21:51:32]

Description was changed from

==========
Add POINTER_WHEEL_CHANGED event to mojo.

Also creating a MouseWheelEvent instead of a MouseEvent
from PointerEvent if its type is POINTER_WHEEL_CHANGED 
to avoid stack overflow.

BUG=642486
TEST=events_unittests
==========

to

==========
Add POINTER_WHEEL_CHANGED event to mojo.

Also creating a MouseWheelEvent instead of a MouseEvent
from PointerEvent if its type is POINTER_WHEEL_CHANGED 
to avoid stack overflow.

BUG=642486
TEST=events_unittests
==========

[commit-bot: I haz the power, 2016-09-01 21:51:33]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2016-09-01 21:55:29]

Description was changed from

==========
Add POINTER_WHEEL_CHANGED event to mojo.

Also creating a MouseWheelEvent instead of a MouseEvent
from PointerEvent if its type is POINTER_WHEEL_CHANGED 
to avoid stack overflow.

BUG=642486
TEST=events_unittests
==========

to

==========
Add POINTER_WHEEL_CHANGED event to mojo.

Also creating a MouseWheelEvent instead of a MouseEvent
from PointerEvent if its type is POINTER_WHEEL_CHANGED
to avoid stack overflow.

BUG=642486
TEST=events_unittests

Committed: https://crrev.com/ec96963b90a87eb8e30dd9e8b74f5951eeda14f2
Cr-Commit-Position: refs/heads/master@{#416072}
==========

[commit-bot: I haz the power, 2016-09-01 21:55:30]

Patchset 3 (id:??) landed as
https://crrev.com/ec96963b90a87eb8e30dd9e8b74f5951eeda14f2
Cr-Commit-Position: refs/heads/master@{#416072}

[riajiang, 2016-09-02 18:42:12]

Description was changed from

==========
Add POINTER_WHEEL_CHANGED event to mojo.

Also creating a MouseWheelEvent instead of a MouseEvent
from PointerEvent if its type is POINTER_WHEEL_CHANGED
to avoid stack overflow.

BUG=642486
TEST=events_unittests

Committed: https://crrev.com/ec96963b90a87eb8e30dd9e8b74f5951eeda14f2
Cr-Commit-Position: refs/heads/master@{#416072}
==========

to

==========
Add POINTER_WHEEL_CHANGED event to mojo.

Also creating a MouseWheelEvent instead of a MouseEvent
from PointerEvent if its type is POINTER_WHEEL_CHANGED
to avoid stack overflow.

BUG=642486
TEST=events_unittests + manual

Committed: https://crrev.com/ec96963b90a87eb8e30dd9e8b74f5951eeda14f2
Cr-Commit-Position: refs/heads/master@{#416072}
==========