Adds capture to the mojo window_manager.

Adds capture to the mojo window_manager.

This adds a CaptureController which manages capture, puts a checkbox
that makes a window have capture in the wm_flow demo, and ports the
relevant unit tests for FocusController.

BUG=442545
R=sky@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/f88a2fb808a14aabee040ed7b0999ee672d9d945

[Elliot Glaysher, 2014-12-16 00:57:48]

erg@chromium.org changed reviewers:
+ sky@chromium.org

[sky, 2014-12-16 03:44:20]

https://codereview.chromium.org/805123003/diff/20001/mojo/services/view_manag...
File mojo/services/view_manager/public/cpp/view.h (right):

https://codereview.chromium.org/805123003/diff/20001/mojo/services/view_manag...
mojo/services/view_manager/public/cpp/view.h:106: View* GetRoot();
Inline and const_cast like we do for other types? See ui/views/view.h:child_at
for what I mean.

https://codereview.chromium.org/805123003/diff/20001/services/window_manager/...
File services/window_manager/capture_controller.cc (right):

https://codereview.chromium.org/805123003/diff/20001/services/window_manager/...
services/window_manager/capture_controller.cc:60: void
CaptureController::NotifyCaptureChange(mojo::View* old_capture,
How about swapping order so it's consistant with OnCaptureChanged. That said, I
actually prefer this ordering (old, new). But it should match the observer
function, so swap that one too.

https://codereview.chromium.org/805123003/diff/20001/services/window_manager/...
File services/window_manager/focus_controller.cc (right):

https://codereview.chromium.org/805123003/diff/20001/services/window_manager/...
services/window_manager/focus_controller.cc:80: if (view &&
(GetCaptureView(view) == view) && focused_view_)
This was was recently nuked from chrome:
https://codereview.chromium.org/753223004/diff/60001/ui/wm/core/focus_control...
.

[Elliot Glaysher, 2014-12-16 18:54:01]

ptal

(Nuked the capture code and the associated unit test.)

[sky, 2014-12-16 19:02:41]

LGTM

[Elliot Glaysher, 2014-12-16 19:09:39]

Committed patchset #3 (id:40001) manually as
f88a2fb808a14aabee040ed7b0999ee672d9d945 (presubmit successful).