Make rb_shell_player_get_playing_time fail if the player can't figure out

2007-12-16  Jonathan Matthew  <jonathan@d14n.org>

        * shell/rb-shell-player.c: (rb_shell_player_get_playing_time),
        (rb_shell_player_error_get_type):
        * shell/rb-shell-player.h:
        Make rb_shell_player_get_playing_time fail if the player can't figure
        out the playback position.

        * plugins/audioscrobbler/rb-audioscrobbler.c:
        (maybe_add_current_song_to_queue),
        (rb_audioscrobbler_song_changed_cb):
        If we don't get a playback position, assume we're at the start of the
        track.  From #499745.

svn path=/trunk/; revision=5492