Get rid of PrefService::GetMutableDictionary/GetMutableList
Get rid of PrefService::GetMutableDictionary/GetMutableList

BUG=77914
TEST=none, trybots remain green

Review URL: http://codereview.chromium.org/6792017

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@80441 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