incrementPitch(angle) {
    if (!this.vrWebgl_) {
      shaka.log.alwaysWarn('Not playing VR content');
      return;
    }
    this.vrWebgl_.rotateViewGlobal(
        0, angle * shaka.ui.VRManager.TO_RADIANS_, 0);
  }
Increment the pitch in X angle in degrees.

@param {number} angle