Speculative fix for MaxTouchPoints returning incorrect value on Windows.

Speculative fix for MaxTouchPoints returning incorrect value on Windows.

Windows 7 appears to sometimes return an incorrect value for max touch
points, returning 1 when there's in fact no touch devices present. This
breaks some web pages that use a non-zero number of touch points as a
signal that the devices has a touch screen. As this is specific to certain
Win7 configurations, I don't have a repro; however, reports in the bug
show that the SM_DIGITIZER setting does indeed return the correct status
of "no touchscreen". In light of this, we speculatively return 0 touches
if there's no touchscreen device present.

BUG=352942
Committed: https://crrev.com/c7c9e396975f37ef865bf4cea63ac64d93295a3d
Cr-Commit-Position: refs/heads/master@{#294467}

[bokan, 2014-09-11 18:36:13]

Sadrul, PTAL. Thanks.

[bokan, 2014-09-11 18:36:44]

bokan@chromium.org changed reviewers:
+ sadrul@chromium.org

[bokan, 2014-09-11 18:36:44]

Actually adding sadrul@...

[sadrul, 2014-09-11 19:33:37]

/cc +girard@

lgtm

[bokan, 2014-09-11 19:35:07]

The CQ bit was checked by bokan@chromium.org

[girard, 2014-09-11 19:51:30]

On 2014/09/11 19:33:37, sadrul wrote:
> /cc +girard@
> 
> lgtm

lgtm

[commit-bot: I haz the power, 2014-09-11 19:55:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/563853002/1

[commit-bot: I haz the power, 2014-09-11 21:18:09]

Committed patchset #1 (id:1) as b74e6fccfb025037d6b419a592cdd494ce4c4a67

[commit-bot: I haz the power, 2014-09-11 21:40:52]

Patchset 1 (id:??) landed as
https://crrev.com/c7c9e396975f37ef865bf4cea63ac64d93295a3d
Cr-Commit-Position: refs/heads/master@{#294467}