The ornamental design for a headphonecordsleeve, as shown and described.
FIG. 1 is a top perspective view of a headphone cord sleeve showing my new design in combination with headphones;
FIG. 2 is a top perspective view of the headphone cord sleeve;
FIG. 3 is a front perspective view thereof;
FIG. 4 is a back view thereof;
FIG. 5 is a side view thereof;
FIG. 6 is a side view thereof;
FIG. 7 is a top view thereof; and,
FIG. 8 is a bottom view thereof.
Those portions of the figures that are presented in broken lines merely illustrate the environment of the design and are not part of the claimed design.