Rebind mus keyboard shortcut for dump ServerWindow hierarchy to Ctrl-Alt-Shift-M

Rebind mus keyboard shortcut for dump ServerWindow hierarchy to Ctrl-Alt-Shift-M

This avoids a DCHECK on startup when running chrome --mash --ash-debug-shortcuts.
The previous accelerator Ctrl-Alt-Shift-S was already used by ash.

BUG=633270
TEST=manual

[James Cook, 2016-08-01 18:02:55]

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

[commit-bot: I haz the power, 2016-08-01 18:03:18]

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

[James Cook, 2016-08-01 18:05:41]

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

[James Cook, 2016-08-01 18:05:42]

sky, PTAL

This is just a band-aid to fix the startup DCHECK. I still get a DCHECK failure
in the window server after hitting the key (?). It would also be nice if the
duplicate-key DCHECK printed more information.

[commit-bot: I haz the power, 2016-08-01 19:00:22]

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

[commit-bot: I haz the power, 2016-08-01 19:00:23]

Dry run: This issue passed the CQ dry run.

[sky, 2016-08-01 20:43:20]

https://codereview.chromium.org/2197203003/diff/1/services/ui/ws/window_manag...
File services/ui/ws/window_manager_state.cc (right):

https://codereview.chromium.org/2197203003/diff/1/services/ui/ws/window_manag...
services/ui/ws/window_manager_state.cc:370: ui::mojom::KeyboardCode::M,
ui::mojom::kEventFlagControlDown |
I think the wm should be able to override debug accelerators, otherwise we get
errors like we're seeing.

I also think debug accelerators should always be processed. So, if the wm binds
an accelerator mus defines both are processed.

[James Cook, 2016-08-01 21:25:59]

On 2016/08/01 20:43:20, sky wrote:
>
https://codereview.chromium.org/2197203003/diff/1/services/ui/ws/window_manag...
> File services/ui/ws/window_manager_state.cc (right):
> 
>
https://codereview.chromium.org/2197203003/diff/1/services/ui/ws/window_manag...
> services/ui/ws/window_manager_state.cc:370: ui::mojom::KeyboardCode::M,
> ui::mojom::kEventFlagControlDown |
> I think the wm should be able to override debug accelerators, otherwise we get
> errors like we're seeing.
> 
> I also think debug accelerators should always be processed. So, if the wm
binds
> an accelerator mus defines both are processed.

OK, I'll abandon this CL.