Fix crash that occurs when the about:network window is closed while still tracking network jobs.
Fix crash that occurs when the about:network window is closed while still
tracking network jobs.

BUG=9446
R=brettw

Review URL: http://codereview.chromium.org/45072

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@12752 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser