function ResizeObservation(target) {
            /**
             * Broadcasted width of content rectangle.
             *
             * @type {number}
             */
            this.broadcastWidth = 0;
            /**
             * Broadcasted height of content rectangle.
             *
             * @type {number}
             */
            this.broadcastHeight = 0;
            /**
             * Reference to the last observed content rectangle.
             *
             * @private {DOMRectInit}
             */
            this.contentRect_ = createRectInit(0, 0, 0, 0);
            this.target = target;
        }
Creates an instance of ResizeObservation.

@param {Element} target - Element to be observed.