Fix bug with mismatching types in preferences.
Fix bug with mismatching types in preferences.

When actual type of data in preferences is different from
what chrome expects (for example string instead of dictionary)
chrome crashes.

Review URL: http://codereview.chromium.org/2757007

git-svn-id: http://src.chromium.org/svn/trunk/src@49401 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 6763f71305016eadd4fb23b22f81105efc66e3f6
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