The prebuilt files include `web/pdf_viewer.js` with some viewer APIs. Those are missing from type declarations.
.src(
            [
              "extensions/chromium/**/*.{html,js,css,png}",
              "extensions/chromium/preferences_schema.json",
            ],
            { base: "extensions/chromium/" }
          )
          .pipe(gulp.dest(CHROME_BUILD_DIR)),
      ]);
    }
  )
);
gulp.task("jsdoc", function (done) {
  console.log();
  console.log("### Generating documentation (JSDoc)");
  const JSDOC_FILES = ["src/doc_helper.js", "src/display/api.js"];
  rimraf(JSDOC_BUILD_DIR, function () {
    mkdirp(JSDOC_BUILD_DIR).then(function () {
      const command =
        '"node_modules/.bin/jsdoc" -d ' +
        JSDOC_BUILD_DIR +
        " " +
        JSDOC_FILES.join(" ");
      exec(command, done);
    });
  });
});
gulp.task("types", function (done) {
  console.log("### Generating TypeScript definitions using `tsc`");
  const args = [