[Extensions] Build glib message pump on Ozone

The GLib mainloop is a nice to have on the Extension Process (only) to ease
the integration with DBus based services.

The patch won't make glib the default, but will make it possible
to use it if explicitly declared.
Merge pull request #160 from tmpsantos/glib_mainloop

[Extensions] Build glib message pump on Ozone
[TEMP] Publish DEPS for Chromium 36.0.1985.18

Related to XWALK-1894