constructor() {
    /**
     * @private {?OffscreenCanvas} canvas used to create the 2D context.
     *     Initialized in init.
     */
    this.canvas_ = null;
    /**
     * @private {?CanvasRenderingContext2D} the 2D context used to draw the
     *     effect. Initialized in init.
     */
    this.ctx_ = null;
    /** @private {string} */
    this.debugPath_ = 'debug.pipeline.frameTransform_';
  }
Applies a picture-frame effect using CanvasRenderingContext2D.
@implements {FrameTransform} in pipeline.js