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)

setVerbosityLevel(params.verbosity);
  if (!worker) {
    const workerParams = {
      verbosity: params.verbosity,
      port: GlobalWorkerOptions.workerPort,
    };
    
    
    worker = workerParams.port
      ? PDFWorker.fromPort(workerParams)
      : new PDFWorker(workerParams);
    task._worker = worker;
  }
  const docId = task.docId;
  worker.promise
    .then(function () {
      if (task.destroyed) {
        throw new Error("Loading aborted");
      }
      const workerIdPromise = _fetchDocument(
        worker,
        params,
        rangeTransport,
        docId
      );
      const networkStreamPromise = new Promise(function (resolve) {
        let networkStream;
        if (rangeTransport) {
          networkStream = new PDFDataTransportStream(