Adding support for sending horizonatal mouse wheel information in Chrome ASH on Windows 8.

Adding support for sending horizonatal mouse wheel information in Chrome ASH on Windows 8.

Currently using the horizontal mouse wheel also causes vertical scrolling. With this change we send over
a flag in the mouse messages which indicates if horizontal scrolling is being done and if yes we create
the right MouseWheelEvent instance.

BUG=332797
R=cpu@chromium.org, jschuh@chromium.org, sky@chromium.org, cpu

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=246730

[cpu_(ooo_6.6-7.5), 2014-01-19 03:11:31]

lgtm

[commit-bot: I haz the power, 2014-01-19 03:11:52]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ananta@chromium.org/141953014/1

[commit-bot: I haz the power, 2014-01-19 03:27:31]

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

[ananta, 2014-01-19 15:35:28]

+sky for ui\aura OWNERS review.
+jschuh for metro_viewer_messages.h

[sky, 2014-01-21 15:43:24]

LGTM

[jschuh, 2014-01-21 23:53:16]

ipc security lgtm

[ananta, 2014-01-23 23:46:26]

Committed patchset #1 manually as r246730 (presubmit successful).