mash: Repost mouse pressed event when closing Ash system tray

mash: Repost mouse pressed event when closing Ash system tray

* Change OnWindowInputEventAck to take an enum for the event result (handled,
  unhandled, or repost) instead of a bool. Plumb this through the event dispatch
  system.
* Always cache the input event awaiting acknowledgement in WindowManagerState,
  not just for accelerator events.
* Repost input events at their original location, rather than their transformed
  location, so they can target other windows correctly.
* Introduce a MessageLoop::NestingObserver so that mus client apps can
  immediately acknowledge input events that trigger a nested message.

For automated tests:
* Track the location of events when recording WindowTreeClient changes.
* Add a SurfacesState to WindowManagerStateTest so that hit testing works
  properly.

BUG=599142
TEST=Unit tests added to base_unittests and mus_ws_unittests. Manual test is
to open system tray menu, then click on Quick Launch close box. Both will
close.

[James Cook, 2016-04-14 21:30:32]

Description was changed from

==========
mash: Repost mouse pressed event when closing Ash system tray

* Change OnWindowInputEventAck to take an enum for the event result (handled,
  unhandled, or repost) instead of a bool. Plumb this through the event dispatch
  system.
* Always cache the input event awaiting acknowledgement in WindowManagerState,
  not just for accelerator events.
* Repost input events at their original location, rather than their transformed
  location, so they can target other windows correctly.
* Introduce a MessageLoop::NestingObserver so that mus client apps can
  immediately acknowledge input events that trigger a nested message.

For automated tests:
* Track the location of events when recording WindowTreeClient changes.
* Add a SurfacesState to WindowManagerStateTest so that hit testing works
  properly.

Manual test:
Run mash. Open system tray menu. Click on the Quick Launcher close box. Both
the system tray and Quick Launch should close.

BUG=599142
TEST=Unit tests added to base_unittests and mus_ws_unittests.
==========

to

==========
mash: Repost mouse pressed event when closing Ash system tray

* Change OnWindowInputEventAck to take an enum for the event result (handled,
  unhandled, or repost) instead of a bool. Plumb this through the event dispatch
  system.
* Always cache the input event awaiting acknowledgement in WindowManagerState,
  not just for accelerator events.
* Repost input events at their original location, rather than their transformed
  location, so they can target other windows correctly.
* Introduce a MessageLoop::NestingObserver so that mus client apps can
  immediately acknowledge input events that trigger a nested message.

For automated tests:
* Track the location of events when recording WindowTreeClient changes.
* Add a SurfacesState to WindowManagerStateTest so that hit testing works
  properly.

BUG=599142
TEST=Unit tests added to base_unittests and mus_ws_unittests. Manual test is
to open system tray menu, then click on Quick Launch close box. Both will
close.
==========

[James Cook, 2016-04-14 21:44:55]

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

[James Cook, 2016-04-14 21:44:56]

sky, please take a look.

[James Cook, 2016-04-14 21:45:05]

The CQ bit was checked by jamescook@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-04-14 21:45:54]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1883263002/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1883263002/40001

[commit-bot: I haz the power, 2016-04-14 21:51:31]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-04-14 21:51:32]

Dry run: Try jobs failed on following builders:
  cast_shell_linux on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/cast_shell_linu...)
  linux_chromium_clobber_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  linux_chromium_gn_chromeos_rel on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  linux_chromium_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[James Cook, 2016-04-27 15:13:56]

jamescook@chromium.org changed reviewers:
- sky@chromium.org

[James Cook, 2016-04-27 15:15:06]

Abandoned. I've extracted the useful bits of this into other CLs (notably the
messageloop / event acking bits into https://codereview.chromium.org/1891233006/
).