Make FaviconService a scoped_ptr and remove call to base::RefCountedThreadSafe

BUG=79886


Review URL: http://codereview.chromium.org/7900002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@101483 0039d316-1c4b-4281-b951-d872f2087c98
5 files changed