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)

let view;
  switch (mode) {
    case "thumbs":
      view = SidebarView.THUMBS;
      break;
    case "bookmarks":
    case "outline": 
      view = SidebarView.OUTLINE;
      break;
    case "attachments": 
      view = SidebarView.ATTACHMENTS;
      break;
    case "layers": 
      view = SidebarView.LAYERS;
      break;
    case "none":
      view = SidebarView.NONE;
      break;
    default:
      console.error('Invalid "pagemode" hash parameter: ' + mode);
      return;
  }
  PDFViewerApplication.pdfSidebar.switchView(view,  true);
}
function webViewerNamedAction(evt) {