GTK: speculative fix for browser test crashes on buildbot.
GTK: speculative fix for browser test crashes on buildbot.

Disconnect some more signal handlers on shutdown.

BUG=40735
TEST=watch waterfall

Review URL: http://codereview.chromium.org/1542019

git-svn-id: http://src.chromium.org/svn/trunk/src@43893 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: a315ef1c6d22bfd6fa3c384531c7ecc305f7932f
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser