fixup! Trebuchet: Implement gesture hint toggle

When taskbar height is 0, callback in the following code never runs:

ViewUtils.postFrameDrawn(postResumeLastTask,
        () -> mStateCallback.setState(STATE_RESUME_LAST_TASK));

Change-Id: I98833b7ae1e30554717a1c5a7d1770fb4e43b3a2