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)

id: pageNum,
            scale,
            defaultViewport: viewport.clone(),
            optionalContentConfigPromise,
            renderingQueue: this.renderingQueue,
            textLayerFactory,
            textLayerMode: this.textLayerMode,
            annotationLayerFactory: this,
            xfaLayerFactory,
            structTreeLayerFactory: this,
            imageResourcesPath: this.imageResourcesPath,
            renderInteractiveForms: this.renderInteractiveForms,
            renderer: this.renderer,
            enableWebGL: this.enableWebGL,
            useOnlyCssZoom: this.useOnlyCssZoom,
            maxCanvasPixels: this.maxCanvasPixels,
            l10n: this.l10n,
          });
          this._pages.push(pageView);
        }
        
        
        
        const firstPageView = this._pages[0];
        if (firstPageView) {
          firstPageView.setPdfPage(firstPdfPage);
          this.linkService.cachePageRef(1, firstPdfPage.ref);
        }
        if (this._spreadMode !== SpreadMode.NONE) {
          this._updateSpreadMode();