onCopyButtonClick() {
    this._dom.fireEventOn('lh-analytics', this._dom.document(), {
      name: 'copy',
    });

    try {
      if (this._dom.document().queryCommandSupported('copy')) {
        this._copyAttempt = true;

        // Note: In Safari 10.0.1, execCommand('copy') returns true if there's
        // a valid text selection on the page. See http://caniuse.com/#feat=clipboard.
        if (!this._dom.document().execCommand('copy')) {
          this._copyAttempt = false; // Prevent event handler from seeing this as a copy attempt.

          this._dom.fireEventOn('lh-log', this._dom.document(), {
            cmd: 'warn', msg: 'Your browser does not support copy to clipboard.',
          });
        }
      }
    } catch (e) {
      this._copyAttempt = false;
      this._dom.fireEventOn('lh-log', this._dom.document(), {cmd: 'log', msg: e.message});
    }
  }
Copies the report JSON to the clipboard (if supported by the browser).