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)

this.pdfDocumentProperties = new PDFDocumentProperties(
      appConfig.documentProperties,
      this.overlayManager,
      eventBus,
      this.l10n
    );
    this.pdfCursorTools = new PDFCursorTools({
      container,
      eventBus,
      cursorToolOnLoad: AppOptions.get("cursorToolOnLoad"),
    });
    this.toolbar = new Toolbar(appConfig.toolbar, eventBus, this.l10n);
    this.secondaryToolbar = new SecondaryToolbar(
      appConfig.secondaryToolbar,
      container,
      eventBus
    );
    if (this.supportsFullscreen) {
      this.pdfPresentationMode = new PDFPresentationMode({
        container,
        pdfViewer: this.pdfViewer,
        eventBus,
      });
    }
    this.passwordPrompt = new PasswordPrompt(
      appConfig.passwordOverlay,
      this.overlayManager,
      this.l10n,
      this.isViewerEmbedded
    );