DOMUI prefs: Fix missing unload listener on the homepage field
DOMUI prefs: Fix missing unload listener on the homepage field

We used to get this for free as part of the pref-linking object decoration, but after the fixes for managed preferences the URL field is no longer a pref-linked field, so we need to add the unload handler directly.

BUG=60636
TEST=Change the homepage in DOMUI prefs, and close the tab without changing focus.

Review URL: http://codereview.chromium.org/4119002

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@63915 0039d316-1c4b-4281-b951-d872f2087c98

adobe/chromium,adobe/chromium,yitian134/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,ropik/chromium,gavinp/chromium,yitian134/chromium,gavinp/chromium,yitian134/chromium,gavinp/chromium,adobe/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,yitian134/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,yitian134/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,ropik/chromium,gavinp/chromium,adobe/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,ropik/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,ropik/chromium,ropik/chromium,yitian134/chromium,ropik/chromium,gavinp/chromium,gavinp/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,ropik/chromium,yitian134/chromium,ropik/chromium,gavinp/chromium