Only target ui::ET_GESTURE_END to the default gesture handler

Only target ui::ET_GESTURE_END to the default gesture handler

If no gesture handler has been established prior to RootView
receiving a ui::ET_GESTURE_END event, do not perform any
targeting based on the event's location (and therefore do not
dispatch this event to any view); GESTURE_END should only
ever be targeted and dispatched to the gesture handler set
by a previous gesture.

BUG=409918
TEST=ViewTargeterTest.ViewTargeterForGestureEvents,
     WidgetTest.GestureBeginAndEndEvents,
     WidgetTest.DisabledGestureEventTarget

Committed: https://crrev.com/906a3939392344cc829470aa99819b9d559196f5
Cr-Commit-Position: refs/heads/master@{#292983}

[tdanderson, 2014-09-02 18:11:39]

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

[tdanderson, 2014-09-02 18:11:39]

Sadrul, PTAL.

[sadrul, 2014-09-02 18:21:06]

lgtm

[tdanderson, 2014-09-02 18:21:22]

The CQ bit was checked by tdanderson@chromium.org

[commit-bot: I haz the power, 2014-09-02 18:21:54]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/tdanderson@chromium.org/533793002/1

[commit-bot: I haz the power, 2014-09-02 20:02:59]

Committed patchset #1 (id:1) as 2a1a37022a7b61a14ccdc396cfbdf17278bd8924

[commit-bot: I haz the power, 2014-09-10 03:20:17]

Patchset 1 (id:??) landed as
https://crrev.com/906a3939392344cc829470aa99819b9d559196f5
Cr-Commit-Position: refs/heads/master@{#292983}