Connect mojo:debugger to window_manager only when requested.

Connect mojo:debugger to window_manager only when requested.

This patch makes mojo:debugger automatically connect to window_manager
only when run by skydb, so that running the debugger for tracing and
profiling doesn't bring the side-effect of spawning window_manager.

Note that we might in the future change this to make the connection to
window_manager lazy when load() or reload() is requested, but this would
require a more involved change to skydb. The way taken in this patch
doesn't change the skydb codepath while enabling usage of debugger for
interactive tracing / profiling.

R=abarth@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/007b11a3f7742dd40ac20560d35ba37e7791d82b

[ppi, 2015-06-02 14:44:11]

ppi@chromium.org changed reviewers:
+ abarth@chromium.org, qsr@chromium.org

[ppi, 2015-06-02 14:44:45]

Hi Ben, Adam,

wdyt?

[abarth-chromium, 2015-06-02 15:05:17]

lgtm

[ppi, 2015-06-02 15:40:09]

Committed patchset #1 (id:1) manually as
007b11a3f7742dd40ac20560d35ba37e7791d82b (presubmit successful).