Change the way the ToplevelEventHandler is hooked up. It is now both a pre- and post-target event h…

Change the way the ToplevelEventHandler is hooked up. It is now both a pre- and post-target event handler.

Most drag logic still occurs pre-target, but initiation occurs post-target, and only if the target chose not to cancel default behavior.

This allows us to forward all events to the target and perform window moving D&D after the fact, while consuming spurious events during the drag operation. Useful for Apps V2 frames.

http://crbug.com/147653
R=sky@chromium.org,sadrul@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=156401

[sadrul, 2012-09-12 18:19:33]

Left a comment about invoking the default-handler.

The rest of the change should not affect touch/gestures. So those LGTM

http://codereview.chromium.org/10911256/diff/5001/ui/base/events/event.cc
File ui/base/events/event.cc (right):

http://codereview.chromium.org/10911256/diff/5001/ui/base/events/event.cc#new...
ui/base/events/event.cc:57: return event.phase() == EP_POSTTARGET &&
event.result() != ER_UNHANDLED;
Right now, the default handler triggers event if one of the pre-target handlers
return ER_HANDLED. So this check should be !(event.result() & ER_CONSUMED)
(EventDispatcher::ProcessEvent has a comment explaining the current behaviour)

[Ben Goodger (Google), 2012-09-12 18:39:53]

http://codereview.chromium.org/10911256/diff/5001/ui/base/events/event.cc
File ui/base/events/event.cc (right):

http://codereview.chromium.org/10911256/diff/5001/ui/base/events/event.cc#new...
ui/base/events/event.cc:57: return event.phase() == EP_POSTTARGET &&
event.result() != ER_UNHANDLED;
But this function won't even be called if event.result() & ER_CONSUMED, right?

Consumed stops propagation, handled just says "next layer up, don't do the
default thing but keep propagating".

[sadrul, 2012-09-12 18:47:36]

http://codereview.chromium.org/10911256/diff/5001/ui/base/events/event.cc
File ui/base/events/event.cc (right):

http://codereview.chromium.org/10911256/diff/5001/ui/base/events/event.cc#new...
ui/base/events/event.cc:57: return event.phase() == EP_POSTTARGET &&
event.result() != ER_UNHANDLED;
On 2012/09/12 18:39:53, Ben Goodger (Google) wrote:
> But this function won't even be called if event.result() & ER_CONSUMED, right?
> 
> Consumed stops propagation, handled just says "next layer up, don't do the
> default thing but keep propagating".

Ah yes. For CONSUMED, this wouldn't be called at all, you are right. I missed in
the comments that this is for post-target handling only.

[sky, 2012-09-12 21:25:39]

LGTM

http://codereview.chromium.org/10911256/diff/10002/ash/wm/toplevel_window_eve...
File ash/wm/toplevel_window_event_handler.cc (right):

http://codereview.chromium.org/10911256/diff/10002/ash/wm/toplevel_window_eve...
ash/wm/toplevel_window_event_handler.cc:326: 
nit: remove newline.