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)

if (PDFViewerApplication.pdfSidebar.isThumbnailViewVisible) {
    const pageView = PDFViewerApplication.pdfViewer.getPageView(
       pageNumber - 1
    );
    const thumbnailView = PDFViewerApplication.pdfThumbnailViewer.getThumbnail(
       pageNumber - 1
    );
    if (pageView && thumbnailView) {
      thumbnailView.setImage(pageView);
    }
  }
  if (error) {
    PDFViewerApplication.l10n.get("rendering_error").then(msg => {
      PDFViewerApplication._otherError(msg, error);
    });
  }
  PDFViewerApplication.externalServices.reportTelemetry({
    type: "pageInfo",
    timestamp,
  });
  
  PDFViewerApplication.pdfDocument.getStats().then(function (stats) {
    PDFViewerApplication.externalServices.reportTelemetry({
      type: "documentStats",
      stats,
    });
  });
}
function webViewerPageMode({ mode }) {