s.getTargetSize_();
    tr.b.dispatchSimpleEvent(this, 'drag-handle-resize', true, false);
  },

  applyDelta_(delta) {
    // Apply new size to the target.
    if (this.target_ === this.nextElementSibling) {
      this.currentDraggingSize_ += delta;
    } else {
      this.currentDraggingSize_ -= delta;
    }
    this.setTargetSize_(this.currentDraggingSize_);
  },

  onMouseMove_(e) {
    // Compute the difference in height position.
    const curMousePos = this.horizontal_ ? e.clientY : e.clientX;
    co