First crack at implementing the touch explaration mode.

First crack at implementing the touch explaration mode. See
https://docs.google.com/a/google.com/document/d/1uOphhlascPTfNjsI2QTdeVTp-ANEz-g2rqGli5yVv34/edit#heading=h.a67n1i6wy36k

This includes logging, TODOs, lacks some comments, and generally needs more
cleanup. Also it sounds like this needs to be rewritten using EventRewriters.
The purpose of the initial review is to get feedback on the general approach
and major details of the implementation.

[mfomitchev, 2014-04-11 21:00:58]

https://codereview.chromium.org/225143007/diff/20001/ash/touch/touch_explorat...
File ash/touch/touch_exploration_controller.cc (right):

https://codereview.chromium.org/225143007/diff/20001/ash/touch/touch_explorat...
ash/touch/touch_exploration_controller.cc:40: // TODO: Here and in other cases
we take the flags from the touch event
Question here

https://codereview.chromium.org/225143007/diff/20001/ash/touch/touch_explorat...
ash/touch/touch_exploration_controller.cc:45: event->StopPropagation();
If I don't call StopPropagation() (here and in other places), gestures don't
seem to work.

https://codereview.chromium.org/225143007/diff/20001/ash/touch/touch_explorat...
ash/touch/touch_exploration_controller.cc:90: // TODO: Should I use another
constructor to pass in the flags?
Question here

https://codereview.chromium.org/225143007/diff/20001/ash/touch/touch_explorat...
ash/touch/touch_exploration_controller.cc:169: // TODO: Should I use 
WindowEventDispatcher instead?
Question here

https://codereview.chromium.org/225143007/diff/20001/ash/touch/touch_explorat...
File ash/touch/touch_exploration_controller.h (right):

https://codereview.chromium.org/225143007/diff/20001/ash/touch/touch_explorat...
ash/touch/touch_exploration_controller.h:18: // TODO: How much screen/display
logic (DisplayController::Observer,
Bunch of questions in TODOs here.

[sadrul, 2014-04-14 20:22:11]

I think (hope) switching to using EventRewriter will make the code simpler.

/cc+ kpschoedel@ FYI

What is the desired behaviour for cursor visibility with this change? e.g.
should the cursor be visible at all times, no matter how many touch-points are
active? Or be visible when just one point is active, but invisible for more than
one fingers, etc.? tdanderson@ should be able to help with getting the correct
behaviour for that.

https://codereview.chromium.org/225143007/diff/20001/ash/touch/touch_explorat...
File ash/touch/touch_exploration_controller.cc (right):

https://codereview.chromium.org/225143007/diff/20001/ash/touch/touch_explorat...
ash/touch/touch_exploration_controller.cc:40: // TODO: Here and in other cases
we take the flags from the touch event
On 2014/04/11 21:00:58, mfomitchev wrote:
> Question here

Yes. The EventRewriter implementation should do the same. It may be a good idea
to set the IS_SYNTHETIZED and/or FROM_TOUCH flags on the mouse-event created.

https://codereview.chromium.org/225143007/diff/20001/ash/touch/touch_explorat...
ash/touch/touch_exploration_controller.cc:45: event->StopPropagation();
On 2014/04/11 21:00:58, mfomitchev wrote:
> If I don't call StopPropagation() (here and in other places), gestures don't
> seem to work.

Yeah. We need to stop propagating the touch-event to make sure it doesn't
contribute to any gestures.

https://codereview.chromium.org/225143007/diff/20001/ash/touch/touch_explorat...
ash/touch/touch_exploration_controller.cc:54: GenerateMouseEvent(
WindowEventDispatcher takes care of dispatching mouse-enter/exit events from
mouse-move events. If that is working correctly, you shouldn't need to generate
the ENTER/EXIT events from here.

https://codereview.chromium.org/225143007/diff/20001/ash/touch/touch_explorat...
ash/touch/touch_exploration_controller.cc:169: // TODO: Should I use 
WindowEventDispatcher instead?
On 2014/04/11 21:00:58, mfomitchev wrote:
> Question here

This is fine.

https://codereview.chromium.org/225143007/diff/20001/ash/touch/touch_explorat...
File ash/touch/touch_exploration_controller.h (right):

https://codereview.chromium.org/225143007/diff/20001/ash/touch/touch_explorat...
ash/touch/touch_exploration_controller.h:18: // TODO: How much screen/display
logic (DisplayController::Observer,
On 2014/04/11 21:00:58, mfomitchev wrote:
> Bunch of questions in TODOs here.

Unsure. oshima@/dnicoara@ would have good answers.