Fix crash in HungRendererDialogGtk when contents_ == NULL.
Fix crash in HungRendererDialogGtk when contents_ == NULL.

BUG=chromium-os:6004
TEST=none

Review URL: http://codereview.chromium.org/3325010

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@58498 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