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diff --git a/browser/components/storybook/.storybook/chrome-uri-loader.js b/browser/components/storybook/.storybook/chrome-uri-loader.js
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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+/* eslint-env node */
+
+/**
+ * This file contains a webpack loader which has the goal of rewriting chrome://
+ * URIs to local paths. This allows JS files loaded in Storybook to load JS
+ * files using their chrome:// URI. Using the chrome:// URI is avoidable in many
+ * cases, however in some cases such as importing the lit.all.mjs file from
+ * browser/components/ there is no way to avoid it on the Firefox side.
+ *
+ * This loader depends on the `./mach storybook manifest` step to generate the
+ * rewrites.js file. That file exports an object with the files we know how to
+ * rewrite chrome:// URIs for.
+ *
+ * This loader allows code like this to work with storybook:
+ *
+ *     import { html } from "chrome://global/content/vendor/lit.all.mjs";
+ *     import "chrome://global/content/elements/moz-button-group.mjs";
+ *
+ * In this example the file would be rewritten in the webpack bundle as:
+ *
+ *     import { html } from "toolkit/content/widgets/vendor/lit.all.mjs";
+ *     import "toolkit/content/widgets/moz-button-group/moz-button-group.mjs";
+ */
+
+const path = require("path");
+
+// Object<ChromeURI, LocalPath> - This is generated by `./mach storybook manifest`.
+const rewrites = require("./rewrites.js");
+
+const projectRoot = path.join(process.cwd(), "../../..");
+
+/**
+ * Return an array of the unique chrome:// URIs referenced in this file.
+ *
+ * @param {string} source - The source file to scan.
+ * @returns {string[]} Unique list of chrome:// URIs
+ */
+function getReferencedChromeUris(source) {
+  // We can only rewrite files that get imported. Which means currently we only
+  // support .js and .mjs. In the future we hope to rewrite .css and .svg.
+  const chromeRegex = /chrome:\/\/.*?\.(js|mjs)/g;
+  const matches = new Set();
+  for (let match of source.matchAll(chromeRegex)) {
+    // Add the full URI to the set of matches.
+    matches.add(match[0]);
+  }
+  return [...matches];
+}
+
+/**
+ * Replace references to chrome:// URIs with the relative path on disk from the
+ * project root.
+ *
+ * @this {WebpackLoader} https://webpack.js.org/api/loaders/
+ * @param {string} source - The source file to update.
+ * @returns {string} The updated source.
+ */
+async function rewriteChromeUris(source) {
+  const chromeUriToLocalPath = new Map();
+  // We're going to rewrite the chrome:// URIs, find all referenced URIs.
+  let chromeDependencies = getReferencedChromeUris(source);
+  for (let chromeUri of chromeDependencies) {
+    let localRelativePath = rewrites[chromeUri];
+    if (localRelativePath) {
+      localRelativePath = localRelativePath.replaceAll("\\", "/");
+      // Store the mapping to a local path for this chrome URI.
+      chromeUriToLocalPath.set(chromeUri, localRelativePath);
+      // Tell webpack the file being handled depends on the referenced file.
+      this.addDependency(path.join(projectRoot, localRelativePath));
+    }
+  }
+  // Rewrite the source file with mapped chrome:// URIs.
+  let rewrittenSource = source;
+  for (let [chromeUri, localPath] of chromeUriToLocalPath.entries()) {
+    rewrittenSource = rewrittenSource.replaceAll(chromeUri, localPath);
+  }
+  return rewrittenSource;
+}
+
+/**
+ * The WebpackLoader export. Runs async since apparently that's preferred.
+ *
+ * @param {string} source - The source to rewrite.
+ * @param {Map} sourceMap - Source map data, unused.
+ * @param {Object} meta - Metadata, unused.
+ */
+module.exports = async function chromeUriLoader(source) {
+  // Get a callback to tell webpack when we're done.
+  const callback = this.async();
+  // Rewrite the source async since that appears to be preferred (and will be
+  // necessary once we support rewriting CSS/SVG/etc).
+  const newSource = await rewriteChromeUris.call(this, source);
+  // Give webpack the rewritten content.
+  callback(null, newSource);
+};