Migrate startup URLs pref.

TBRing battre@ for tiny profile_resetter change, other OWNERs appear to be out as well.

TBR=battre

BUG=299290

Review URL: https://codereview.chromium.org/24930003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229536 0039d316-1c4b-4281-b951-d872f2087c98
Added end2end test.

Review URL: https://codereview.chromium.org/25554002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229537 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229537