I was wondering if WebGL is considered stable enough to be enabled by default. It makes some PDFs render much faster and it has been off by default for a while now, so we have had quite some time to test it.

If we decide to enable WebGL by default, we should not forget to update https://github.com/mozilla/pdf.js/blob/master/extensions/chromium/preferences_schema.json#L39 as well.

/cc @yurydelendik 
/cc @Snuffleupagus (because IIRC you were testing WebGL too)

scale = pageWidthScale;
          break;
        case "page-height":
          scale = pageHeightScale;
          break;
        case "page-fit":
          scale = Math.min(pageWidthScale, pageHeightScale);
          break;
        case "auto":
          
          
          const horizontalScale = isPortraitOrientation(currentPage)
            ? pageWidthScale
            : Math.min(pageHeightScale, pageWidthScale);
          scale = Math.min(MAX_AUTO_SCALE, horizontalScale);
          break;
        default:
          console.error(
            `${this._name}._setScale: "${value}" is an unknown zoom value.`
          );
          return;
      }
      this._setScaleUpdatePages(scale, value, noScroll,  true);
    }
  }
  /**
   * Refreshes page view: scrolls to the current page and updates the scale.
   * @private
   */
  _resetCurrentPageView() {