Store WebRTC log list file per profile.

R=jhawkins@chromium.org, joi@chromium.org, xians@chromium.org

Review URL: https://codereview.chromium.org/26892004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229764 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229764