touch: Change how touch-screen capability is processed.

touch: Change how touch-screen capability is processed.

Instead of storing information in TouchFactory (which is X11 specific), store
the maximum number of touch-points supported by a device in platform agnostic
TouchscreenDevice. Use this TouchscreenDevice to compute the maximum number of
simultaneous touch-points supported at runtime.

BUG=none
R=dnicoara@chromium.org, oshima@chromium.org, spang@chromium.org

Committed: https://chromium.googlesource.com/chromium/src/+/cebc1aaf9a532e695f63c9380160e2c1188fd6ac

[sadrul, 2015-01-13 19:03:35]

sadrul@chromium.org changed reviewers:
+ dnicoara@chromium.org, oshima@chromium.org, spang@chromium.org

[sadrul, 2015-01-13 19:03:36]

oshima@ Please review the ash changes.

dnicoara@ Please review the changes in events/devices

spang@ Please review the ozone TODO I am sending your way :)

[dnicoara, 2015-01-13 19:14:21]

lgtm

The code was using -1 before if the number of points couldn't be found. Does
that have any special meaning elsewhere in the code? You are now assigning 0 if
unknown. Would this have any special meaning elsewhere in the code?

[sadrul, 2015-01-13 19:31:13]

On 2015/01/13 19:14:21, dnicoara wrote:
> lgtm
> 
> The code was using -1 before if the number of points couldn't be found. Does
> that have any special meaning elsewhere in the code? You are now assigning 0
if
> unknown. Would this have any special meaning elsewhere in the code?

Good point. Tweaked the defaults to preserve the current behaviour. Thanks!

[oshima, 2015-01-13 19:39:11]

ash lgtm

[spang, 2015-01-13 19:53:58]

What is this used for? Are we regressing something for freon devices in M41?

[sadrul, 2015-01-13 20:07:29]

On 2015/01/13 19:53:58, spang wrote:
> What is this used for?

This is used to implement
http://www.w3.org/TR/pointerevents/#widl-Navigator-maxTouchPoints

> Are we regressing something for freon devices in M41?

Right now, for ozone, we hard-code maxTouchPoints to 11 (see
ui/base/touch/touch_device_ozone.cc). This patch also hardcodes
TouchscreenDevice::touch_points to 11. This info form DeviceDataManager is not
currently used in ozone, but it will be from the cleanup in
https://codereview.chromium.org/815983003/

To summarize: this should not cause a regression.

[spang, 2015-01-13 20:08:04]

On 2015/01/13 20:07:29, sadrul (OOO) wrote:
> On 2015/01/13 19:53:58, spang wrote:
> > What is this used for?
> 
> This is used to implement
> http://www.w3.org/TR/pointerevents/#widl-Navigator-maxTouchPoints
> 
> > Are we regressing something for freon devices in M41?
> 
> Right now, for ozone, we hard-code maxTouchPoints to 11 (see
> ui/base/touch/touch_device_ozone.cc). This patch also hardcodes
> TouchscreenDevice::touch_points to 11. This info form DeviceDataManager is not
> currently used in ozone, but it will be from the cleanup in
> https://codereview.chromium.org/815983003/
> 
> To summarize: this should not cause a regression.

sweet! lgtm

[commit-bot: I haz the power, 2015-01-13 21:55:40]

Patchset 3 (id:??) landed as
https://crrev.com/cebc1aaf9a532e695f63c9380160e2c1188fd6ac
Cr-Commit-Position: refs/heads/master@{#311336}

[sadrul, 2015-01-13 21:55:43]

Committed patchset #3 (id:40001) manually as
cebc1aaf9a532e695f63c9380160e2c1188fd6ac (presubmit successful).