MediaStream API: Changing all ExtraData objects to be owned
Since we do not have any logic that shares ExtraData objects, nor do we
want to support that usage I have changed all RefCounted EDs to be
owned instead.

Review URL: https://codereview.chromium.org/139943007

git-svn-id: svn://svn.chromium.org/blink/trunk@165239 bbb929c8-8fbe-4397-9dbb-9b2b20218538