Move check for gesture end events out of RootViewTargeter

Move check for gesture end events out of RootViewTargeter

Instead of returning a NULL target for a ET_GESTURE_END
in the case where no default gesture handler has been
established, prevent processing in
RootView::OnEventProcessingStarted() by marking the
event as handled.

BUG=417771
TEST=ViewTargeterTest.ViewTargeterForGestureEvents changed,
     WidgetTest.GestureEndEvents changed,
     WidgetTest.GestureEventsNotProcessed changed,
     WidgetTest.DisabledGestureEventTarget changed

Committed: https://crrev.com/c9f8dbb5d34e0b92f4b9818c5ff1e37fc34768f8
Cr-Commit-Position: refs/heads/master@{#297897}

[tdanderson, 2014-10-01 17:50:30]

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

[tdanderson, 2014-10-01 17:50:46]

Sadrul, can you please take a look?

[sadrul, 2014-10-02 19:23:04]

lgtm

https://codereview.chromium.org/619183002/diff/1/ui/events/event_processor.cc
File ui/events/event_processor.cc (right):

https://codereview.chromium.org/619183002/diff/1/ui/events/event_processor.cc...
ui/events/event_processor.cc:29: // dispatch of the event is not permitted.
The comment for OnEventProcessingStarted() already mentions this. You can remove
the comment from here.

[tdanderson, 2014-10-02 19:35:12]

Sadrul, comments addressed, but I do have a response below:

https://codereview.chromium.org/619183002/diff/1/ui/events/event_processor.cc
File ui/events/event_processor.cc (right):

https://codereview.chromium.org/619183002/diff/1/ui/events/event_processor.cc...
ui/events/event_processor.cc:29: // dispatch of the event is not permitted.
On 2014/10/02 19:23:04, sadrul wrote:
> The comment for OnEventProcessingStarted() already mentions this. You can
remove
> the comment from here.

Done. 

I realize it's duplicated documentation, but the reason I added it (and would
like to add more) was because EventProcessor::OnEventFromSource() is the most
central and important method in the whole event processing system. I assume the
frequency of other developers referencing this method during related debugging
would be high, so leaving it as a wall of code feels like a bit of a disservice.

[tdanderson, 2014-10-02 19:35:24]

The CQ bit was checked by tdanderson@chromium.org

[commit-bot: I haz the power, 2014-10-02 19:36:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/619183002/20001

[commit-bot: I haz the power, 2014-10-02 20:50:29]

Committed patchset #2 (id:20001) as c34d721da0a02f7ce05496963c4d09900eda643b

[commit-bot: I haz the power, 2014-10-02 20:50:49]

Patchset 2 (id:??) landed as
https://crrev.com/c9f8dbb5d34e0b92f4b9818c5ff1e37fc34768f8
Cr-Commit-Position: refs/heads/master@{#297897}