Mousewhell on Chrome Android can scroll vertically and horizontally

Allow Mousewheell on Chrome Android to scroll horizontally

We added the horizontal_axis value to the SendMouseWheelEvent method, so that
the mousewheel event now can scroll vertically and horizontally.

BUG=435154
Committed: https://crrev.com/8322d894578d034bdbefd51ff1e2617d02b9d5c9
Cr-Commit-Position: refs/heads/master@{#307998}

[lanwei, 2014-12-11 16:22:24]

Patchset #1 (id:1) has been deleted

[lanwei, 2014-12-11 16:26:14]

lanwei@chromium.org changed reviewers:
+ jdduke@chromium.org, rbyers@chromium.org, tdresser@chromium.org

[jdduke (slow), 2014-12-11 18:36:00]

Thanks, lgtm. I'm not even sure diagonal mousewheel scrolling is a thing, and
even if it is not sure we need to support it.

[tdresser, 2014-12-11 19:00:42]

On 2014/12/11 18:36:00, jdduke wrote:
> Thanks, lgtm. I'm not even sure diagonal mousewheel scrolling is a thing, and
> even if it is not sure we need to support it.

LGTM, but correct Mousewhell -> Mousewheel in the title and CL description.

[Rick Byers, 2014-12-11 19:07:55]

On 2014/12/11 18:36:00, jdduke wrote:
> Thanks, lgtm. I'm not even sure diagonal mousewheel scrolling is a thing, and
> even if it is not sure we need to support it.

Diagonal "mousewheel" scrolling is a thing with touchpads.  If I plug the same
USB touchpad into my pixel I see that diagonal scrolling produces wheel events
with both deltaX and deltaY set.  Ideally it would do the same on Android.

I see we throw away the raw axis values and convert it into one of 4 possible
directions which then get new axis values synthesized in
WebMouseWheelEventBuilder::Build based on 160/3 pixels per tick.  But perhaps
Android doesn't really have support for raw precise deltas.  So maybe it's not
worth going down this path of trying to make touchpads really behave well
(certainly the couple native Android apps I tried didn't seem to be using the
raw deltas for smooth scrolling).

So LGTM.  But separately if you want to try playing with this touchpad and see
what the actual axis values look like on Android, then it might be worth a
separate bug to plumb the raw deltas through properly (and therefore also
support diagonal scrolling).

[Rick Byers, 2014-12-11 19:07:56]

On 2014/12/11 18:36:00, jdduke wrote:
> Thanks, lgtm. I'm not even sure diagonal mousewheel scrolling is a thing, and
> even if it is not sure we need to support it.

Diagonal "mousewheel" scrolling is a thing with touchpads.  If I plug the same
USB touchpad into my pixel I see that diagonal scrolling produces wheel events
with both deltaX and deltaY set.  Ideally it would do the same on Android.

I see we throw away the raw axis values and convert it into one of 4 possible
directions which then get new axis values synthesized in
WebMouseWheelEventBuilder::Build based on 160/3 pixels per tick.  But perhaps
Android doesn't really have support for raw precise deltas.  So maybe it's not
worth going down this path of trying to make touchpads really behave well
(certainly the couple native Android apps I tried didn't seem to be using the
raw deltas for smooth scrolling).

So LGTM.  But separately if you want to try playing with this touchpad and see
what the actual axis values look like on Android, then it might be worth a
separate bug to plumb the raw deltas through properly (and therefore also
support diagonal scrolling).

[jdduke (slow), 2014-12-11 19:20:06]

On 2014/12/11 19:07:56, Rick Byers wrote:
> On 2014/12/11 18:36:00, jdduke wrote:
> > Thanks, lgtm. I'm not even sure diagonal mousewheel scrolling is a thing,
and
> > even if it is not sure we need to support it.
> 
> Diagonal "mousewheel" scrolling is a thing with touchpads.  If I plug the same
> USB touchpad into my pixel I see that diagonal scrolling produces wheel events
> with both deltaX and deltaY set.  Ideally it would do the same on Android.
> 
> I see we throw away the raw axis values and convert it into one of 4 possible
> directions which then get new axis values synthesized in
> WebMouseWheelEventBuilder::Build based on 160/3 pixels per tick.  But perhaps
> Android doesn't really have support for raw precise deltas.  So maybe it's not
> worth going down this path of trying to make touchpads really behave well
> (certainly the couple native Android apps I tried didn't seem to be using the
> raw deltas for smooth scrolling).
> 
> So LGTM.  But separately if you want to try playing with this touchpad and see
> what the actual axis values look like on Android, then it might be worth a
> separate bug to plumb the raw deltas through properly (and therefore also
> support diagonal scrolling).

Hmm, that's right, mousewheel is also for touchpad, bah... Yeah, that's about
what I originally proposed to Lan, though we'd have to tweak the logic if we
want directions unmodded to 45 degrees.

[lanwei, 2014-12-11 20:33:58]

The CQ bit was checked by lanwei@chromium.org

[commit-bot: I haz the power, 2014-12-11 20:35:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/792333004/20001

[commit-bot: I haz the power, 2014-12-11 23:14:55]

Committed patchset #1 (id:20001)

[commit-bot: I haz the power, 2014-12-11 23:16:18]

Patchset 1 (id:??) landed as
https://crrev.com/8322d894578d034bdbefd51ff1e2617d02b9d5c9
Cr-Commit-Position: refs/heads/master@{#307998}