Adds CaptureClientObserver as a way to track changes in capture

Adds CaptureClientObserver as a way to track changes in capture

I'm going to need this for the aura-mus work so that what is the
WindowTreeClient implementation can track capture and update the
server appropriately.

I didn't update the desktop client as I don't think I'll need that one.

BUG=none
TEST=none
R=sadrul@chromium.org

Committed: https://crrev.com/946eb204231b1edae4320dd9ee1e3a3ee9cf6767
Cr-Commit-Position: refs/heads/master@{#426848}

[sky, 2016-10-21 14:46:22]

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

[commit-bot: I haz the power, 2016-10-21 14:46:39]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-21 15:15:58]

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

[commit-bot: I haz the power, 2016-10-21 15:15:58]

Dry run: Try jobs failed on following builders:
  win_chromium_compile_dbg_ng on master.tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_comp...)

[sky, 2016-10-21 16:21:46]

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

[commit-bot: I haz the power, 2016-10-21 16:22:01]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[sadrul, 2016-10-21 16:58:56]

lgtm

https://codereview.chromium.org/2436023003/diff/40001/ash/display/mirror_wind...
File ash/display/mirror_window_controller.cc (right):

https://codereview.chromium.org/2436023003/diff/40001/ash/display/mirror_wind...
ash/display/mirror_window_controller.cc:109: // Returns the current capture
window.
It's weird that we have these comments here.

[sky, 2016-10-21 16:59:29]

https://codereview.chromium.org/2436023003/diff/40001/ash/display/mirror_wind...
File ash/display/mirror_window_controller.cc (right):

https://codereview.chromium.org/2436023003/diff/40001/ash/display/mirror_wind...
ash/display/mirror_window_controller.cc:109: // Returns the current capture
window.
On 2016/10/21 16:58:56, sadrul wrote:
> It's weird that we have these comments here.

Agreed. I'll nuke them.

[sky, 2016-10-21 17:01:53]

The CQ bit was checked by sky@chromium.org

[sky, 2016-10-21 17:01:53]

The patchset sent to the CQ was uploaded after l-g-t-m from sadrul@chromium.org
Link to the patchset: https://codereview.chromium.org/2436023003/#ps60001
(title: "fix comments")

[commit-bot: I haz the power, 2016-10-21 17:02:08]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-21 18:26:00]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2016-10-21 18:42:39]

Description was changed from

==========
Adds CaptureClientObserver as a way to track changes in capture

I'm going to need this for the aura-mus work so that what is the
WindowTreeClient implementation can track capture and update the
server appropriately.

I didn't update the desktop client as I don't think I'll need that one.

BUG=none
TEST=none
R=sadrul@chromium.org
==========

to

==========
Adds CaptureClientObserver as a way to track changes in capture

I'm going to need this for the aura-mus work so that what is the
WindowTreeClient implementation can track capture and update the
server appropriately.

I didn't update the desktop client as I don't think I'll need that one.

BUG=none
TEST=none
R=sadrul@chromium.org

Committed: https://crrev.com/946eb204231b1edae4320dd9ee1e3a3ee9cf6767
Cr-Commit-Position: refs/heads/master@{#426848}
==========

[commit-bot: I haz the power, 2016-10-21 18:42:40]

Patchset 4 (id:??) landed as
https://crrev.com/946eb204231b1edae4320dd9ee1e3a3ee9cf6767
Cr-Commit-Position: refs/heads/master@{#426848}