Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

22 files changed, 5587 insertions, 0 deletions

diff --git a/remote/webdriver-bidi/NewSessionHandler.sys.mjs b/remote/webdriver-bidi/NewSessionHandler.sys.mjs
new file mode 100644
index 0000000000..342419033f
--- /dev/null
+++ b/remote/webdriver-bidi/NewSessionHandler.sys.mjs
@@ -0,0 +1,57 @@
+/* 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/. */
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  WebDriverBiDiConnection:
+    "chrome://remote/content/webdriver-bidi/WebDriverBiDiConnection.sys.mjs",
+  WebSocketHandshake:
+    "chrome://remote/content/server/WebSocketHandshake.sys.mjs",
+});
+
+/**
+ * httpd.js JSON handler for direct BiDi connections.
+ */
+export class WebDriverNewSessionHandler {
+  /**
+   * Construct a new JSON handler.
+   *
+   * @param {WebDriverBiDi} webDriverBiDi
+   *     Reference to the WebDriver BiDi protocol implementation.
+   */
+  constructor(webDriverBiDi) {
+    this.webDriverBiDi = webDriverBiDi;
+  }
+
+  // nsIHttpRequestHandler
+
+  /**
+   * Handle new direct WebSocket connection requests.
+   *
+   * WebSocket clients not using the WebDriver BiDi opt-in mechanism via the
+   * WebDriver HTTP implementation will attempt to directly connect at
+   * `/session`.  Hereby a WebSocket upgrade will automatically be performed.
+   *
+   * @param {Request} request
+   *     HTTP request (httpd.js)
+   * @param {Response} response
+   *     Response to an HTTP request (httpd.js)
+   */
+  async handle(request, response) {
+    const webSocket = await lazy.WebSocketHandshake.upgrade(request, response);
+    const conn = new lazy.WebDriverBiDiConnection(
+      webSocket,
+      response._connection
+    );
+
+    this.webDriverBiDi.addSessionlessConnection(conn);
+  }
+
+  // XPCOM
+
+  get QueryInterface() {
+    return ChromeUtils.generateQI(["nsIHttpRequestHandler"]);
+  }
+}
diff --git a/remote/webdriver-bidi/Realm.sys.mjs b/remote/webdriver-bidi/Realm.sys.mjs
new file mode 100644
index 0000000000..e4924cecdd
--- /dev/null
+++ b/remote/webdriver-bidi/Realm.sys.mjs
@@ -0,0 +1,306 @@
+/* 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/. */
+
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
+
+const lazy = {};
+ChromeUtils.defineESModuleGetters(lazy, {
+  addDebuggerToGlobal: "resource://gre/modules/jsdebugger.sys.mjs",
+});
+
+XPCOMUtils.defineLazyGetter(lazy, "dbg", () => {
+  // eslint-disable-next-line mozilla/reject-globalThis-modification
+  lazy.addDebuggerToGlobal(globalThis);
+  return new Debugger();
+});
+
+/**
+ * @typedef {string} RealmType
+ **/
+
+/**
+ * Enum of realm types.
+ *
+ * @readonly
+ * @enum {RealmType}
+ **/
+export const RealmType = {
+  AudioWorklet: "audio-worklet",
+  DedicatedWorker: "dedicated-worker",
+  PaintWorklet: "paint-worklet",
+  ServiceWorker: "service-worker",
+  SharedWorker: "shared-worker",
+  Window: "window",
+  Worker: "worker",
+  Worklet: "worklet",
+};
+
+function getUUID() {
+  return Services.uuid
+    .generateUUID()
+    .toString()
+    .slice(1, -1);
+}
+
+/**
+ * Base class that wraps any kind of WebDriver BiDi realm.
+ */
+export class Realm {
+  #handleObjectMap;
+  #id;
+
+  constructor() {
+    this.#id = getUUID();
+
+    // Map of unique handles (UUIDs) to objects belonging to this realm.
+    this.#handleObjectMap = new Map();
+  }
+
+  destroy() {
+    this.#handleObjectMap = null;
+  }
+
+  /**
+   * Get the unique identifier of the realm instance.
+   *
+   * @return {string} The unique identifier.
+   */
+  get id() {
+    return this.#id;
+  }
+
+  /**
+   * A getter to get a realm origin.
+   *
+   * It's required to be implemented in the sub class.
+   */
+  get origin() {
+    throw new Error("Not implemented");
+  }
+
+  /**
+   * Ensure the provided object can be used within this realm.
+
+   * @param {Object} object
+   *     Any non-primitive object.
+
+   * @return {Object}
+   *     An object usable in the current realm.
+   */
+  cloneIntoRealm(obj) {
+    return obj;
+  }
+
+  /**
+   * Remove the reference corresponding to the provided unique handle.
+   *
+   * @param {string} handle
+   *     The unique handle of an object reference tracked in this realm.
+   */
+  removeObjectHandle(handle) {
+    this.#handleObjectMap.delete(handle);
+  }
+
+  /**
+   * Get a new unique handle for the provided object, creating a strong
+   * reference on the object.
+   *
+   * @param {Object} object
+   *     Any non-primitive object.
+   * @return {string} The unique handle created for this strong reference.
+   */
+  getHandleForObject(object) {
+    const handle = getUUID();
+    this.#handleObjectMap.set(handle, object);
+    return handle;
+  }
+
+  /**
+   * Get the basic realm information.
+   *
+   * @return {BaseRealmInfo}
+   */
+  getInfo() {
+    return {
+      realm: this.#id,
+      origin: this.origin,
+    };
+  }
+
+  /**
+   * Retrieve the object corresponding to the provided unique handle.
+   *
+   * @param {string} handle
+   *     The unique handle of an object reference tracked in this realm.
+   * @return {Object} object
+   *     Any non-primitive object.
+   */
+  getObjectForHandle(handle) {
+    return this.#handleObjectMap.get(handle);
+  }
+}
+
+/**
+ * Wrapper for Window realms including sandbox objects.
+ */
+export class WindowRealm extends Realm {
+  #globalObject;
+  #globalObjectReference;
+  #sandboxName;
+  #window;
+
+  static type = RealmType.Window;
+
+  /**
+   *
+   * @param {Window} window
+   *     The window global to wrap.
+   * @param {Object} options
+   * @param {string=} options.sandboxName
+   *     Name of the sandbox to create if specified. Defaults to `null`.
+   */
+  constructor(window, options = {}) {
+    const { sandboxName = null } = options;
+
+    super();
+
+    this.#sandboxName = sandboxName;
+    this.#window = window;
+    this.#globalObject =
+      sandboxName === null ? this.#window : this.#createSandbox();
+    this.#globalObjectReference = lazy.dbg.makeGlobalObjectReference(
+      this.#globalObject
+    );
+
+    lazy.dbg.enableAsyncStack(this.#globalObject);
+  }
+
+  destroy() {
+    lazy.dbg.disableAsyncStack(this.#globalObject);
+
+    this.#globalObjectReference = null;
+    this.#globalObject = null;
+    this.#window = null;
+
+    super.destroy();
+  }
+
+  get globalObjectReference() {
+    return this.#globalObjectReference;
+  }
+
+  get origin() {
+    return this.#window.origin;
+  }
+
+  #createDebuggerObject(obj) {
+    return this.#globalObjectReference.makeDebuggeeValue(obj);
+  }
+
+  #createSandbox() {
+    const win = this.#window;
+    const opts = {
+      sameZoneAs: win,
+      sandboxPrototype: win,
+      wantComponents: false,
+      wantXrays: true,
+    };
+
+    return new Cu.Sandbox(win, opts);
+  }
+
+  /**
+   * Clone the provided object into the scope of this Realm (either a window
+   * global, or a sandbox).
+   *
+   * @param {Object} obj
+   *     Any non-primitive object.
+   *
+   * @return {Object}
+   *     The cloned object.
+   */
+  cloneIntoRealm(obj) {
+    return Cu.cloneInto(obj, this.#globalObject);
+  }
+
+  /**
+   * Evaluates a provided expression in the context of the current realm.
+   *
+   * @param {string} expression
+   *     The expression to evaluate.
+   *
+   * @return {Object}
+   *     - evaluationStatus {EvaluationStatus} One of "normal", "throw".
+   *     - exceptionDetails {ExceptionDetails=} the details of the exception if
+   *       the evaluation status was "throw".
+   *     - result {RemoteValue=} the result of the evaluation serialized as a
+   *       RemoteValue if the evaluation status was "normal".
+   */
+  executeInGlobal(expression) {
+    return this.#globalObjectReference.executeInGlobal(expression, {
+      url: this.#window.document.baseURI,
+    });
+  }
+
+  /**
+   * Call a function in the context of the current realm.
+   *
+   * @param {string} functionDeclaration
+   *     The body of the function to call.
+   * @param {Array<Object>} functionArguments
+   *     The arguments to pass to the function call.
+   * @param {Object} thisParameter
+   *     The value of the `this` keyword for the function call.
+   *
+   * @return {Object}
+   *     - evaluationStatus {EvaluationStatus} One of "normal", "throw".
+   *     - exceptionDetails {ExceptionDetails=} the details of the exception if
+   *       the evaluation status was "throw".
+   *     - result {RemoteValue=} the result of the evaluation serialized as a
+   *       RemoteValue if the evaluation status was "normal".
+   */
+  executeInGlobalWithBindings(
+    functionDeclaration,
+    functionArguments,
+    thisParameter
+  ) {
+    const expression = `(${functionDeclaration}).apply(__bidi_this, __bidi_args)`;
+
+    const args = this.cloneIntoRealm([]);
+    for (const arg of functionArguments) {
+      args.push(arg);
+    }
+
+    return this.#globalObjectReference.executeInGlobalWithBindings(
+      expression,
+      {
+        __bidi_args: this.#createDebuggerObject(args),
+        __bidi_this: this.#createDebuggerObject(thisParameter),
+      },
+      {
+        url: this.#window.document.baseURI,
+      }
+    );
+  }
+
+  /**
+   * Get the realm information.
+   *
+   * @return {Object}
+   *     - context {BrowsingContext} The browsing context, associated with the realm.
+   *     - id {string} The realm unique identifier.
+   *     - origin {string} The serialization of an origin.
+   *     - sandbox {string|null} The name of the sandbox.
+   *     - type {RealmType.Window} The window realm type.
+   */
+  getInfo() {
+    const baseInfo = super.getInfo();
+    return {
+      ...baseInfo,
+      context: this.#window.browsingContext,
+      sandbox: this.#sandboxName,
+      type: WindowRealm.type,
+    };
+  }
+}
diff --git a/remote/webdriver-bidi/RemoteValue.sys.mjs b/remote/webdriver-bidi/RemoteValue.sys.mjs
new file mode 100644
index 0000000000..a45f679dc2
--- /dev/null
+++ b/remote/webdriver-bidi/RemoteValue.sys.mjs
@@ -0,0 +1,772 @@
+/* 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/. */
+
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  assert: "chrome://remote/content/shared/webdriver/Assert.sys.mjs",
+  error: "chrome://remote/content/shared/webdriver/Errors.sys.mjs",
+  Log: "chrome://remote/content/shared/Log.sys.mjs",
+});
+
+XPCOMUtils.defineLazyGetter(lazy, "logger", () =>
+  lazy.Log.get(lazy.Log.TYPES.WEBDRIVER_BIDI)
+);
+
+/**
+ * @typedef {Object} OwnershipModel
+ **/
+
+/**
+ * Enum of ownership models supported by the serialization.
+ *
+ * @readonly
+ * @enum {OwnershipModel}
+ **/
+export const OwnershipModel = {
+  None: "none",
+  Root: "root",
+};
+
+function getUUID() {
+  return Services.uuid
+    .generateUUID()
+    .toString()
+    .slice(1, -1);
+}
+
+const TYPED_ARRAY_CLASSES = [
+  "Uint8Array",
+  "Uint8ClampedArray",
+  "Uint16Array",
+  "Uint32Array",
+  "Int8Array",
+  "Int16Array",
+  "Int32Array",
+  "Float32Array",
+  "Float64Array",
+  "BigInt64Array",
+  "BigUint64Array",
+];
+
+/**
+ * Build the serialized RemoteValue.
+ *
+ * @return {Object}
+ *     An object with a mandatory `type` property, and optional `handle`,
+ *     depending on the OwnershipModel, used for the serialization and
+ *     on the value's type.
+ */
+function buildSerialized(type, handle = null) {
+  const serialized = { type };
+
+  if (handle !== null) {
+    serialized.handle = handle;
+  }
+
+  return serialized;
+}
+
+/**
+ * Helper to validate if a date string follows Date Time String format.
+ *
+ * @see https://tc39.es/ecma262/#sec-date-time-string-format
+ *
+ * @param {string} dateString
+ *     String which needs to be validated.
+ *
+ * @throws {InvalidArgumentError}
+ *     If <var>dateString</var> doesn't follow the format.
+ */
+function checkDateTimeString(dateString) {
+  // Check if a date string follows a simplification of
+  // the ISO 8601 calendar date extended format.
+  const expandedYear = "[+-]\\d{6}";
+  const year = "\\d{4}";
+  const YYYY = `${expandedYear}|${year}`;
+  const MM = "\\d{2}";
+  const DD = "\\d{2}";
+  const date = `${YYYY}(?:-${MM})?(?:-${DD})?`;
+  const HH_mm = "\\d{2}:\\d{2}";
+  const SS = "\\d{2}";
+  const sss = "\\d{3}";
+  const TZ = `Z|[+-]${HH_mm}`;
+  const time = `T${HH_mm}(?::${SS}(?:\\.${sss})?(?:${TZ})?)?`;
+  const iso8601Format = new RegExp(`^${date}(?:${time})?$`);
+
+  // Check also if a date string is a valid date.
+  if (Number.isNaN(Date.parse(dateString)) || !iso8601Format.test(dateString)) {
+    throw new lazy.error.InvalidArgumentError(
+      `Expected "value" for Date to be a Date Time string, got ${dateString}`
+    );
+  }
+}
+
+/**
+ * Helper to deserialize value list.
+ *
+ * @see https://w3c.github.io/webdriver-bidi/#deserialize-value-list
+ *
+ * @param {Realm} realm
+ *     The Realm in which the value is deserialized.
+ * @param {Array} serializedValueList
+ *     List of serialized values.
+ *
+ * @return {Array} List of deserialized values.
+ *
+ * @throws {InvalidArgumentError}
+ *     If <var>serializedValueList</var> is not an array.
+ */
+function deserializeValueList(realm, serializedValueList) {
+  lazy.assert.array(
+    serializedValueList,
+    `Expected "serializedValueList" to be an array, got ${serializedValueList}`
+  );
+
+  const deserializedValues = [];
+
+  for (const item of serializedValueList) {
+    deserializedValues.push(deserialize(realm, item));
+  }
+
+  return deserializedValues;
+}
+
+/**
+ * Helper to deserialize key-value list.
+ *
+ * @see https://w3c.github.io/webdriver-bidi/#deserialize-key-value-list
+ *
+ * @param {Realm} realm
+ *     The Realm in which the value is deserialized.
+ * @param {Array} serializedKeyValueList
+ *     List of serialized key-value.
+ *
+ * @return {Array} List of deserialized key-value.
+ *
+ * @throws {InvalidArgumentError}
+ *     If <var>serializedKeyValueList</var> is not an array or
+ *     not an array of key-value arrays.
+ */
+function deserializeKeyValueList(realm, serializedKeyValueList) {
+  lazy.assert.array(
+    serializedKeyValueList,
+    `Expected "serializedKeyValueList" to be an array, got ${serializedKeyValueList}`
+  );
+
+  const deserializedKeyValueList = [];
+
+  for (const serializedKeyValue of serializedKeyValueList) {
+    if (!Array.isArray(serializedKeyValue) || serializedKeyValue.length != 2) {
+      throw new lazy.error.InvalidArgumentError(
+        `Expected key-value pair to be an array with 2 elements, got ${serializedKeyValue}`
+      );
+    }
+    const [serializedKey, serializedValue] = serializedKeyValue;
+    const deserializedKey =
+      typeof serializedKey == "string"
+        ? serializedKey
+        : deserialize(realm, serializedKey);
+    const deserializedValue = deserialize(realm, serializedValue);
+
+    deserializedKeyValueList.push([deserializedKey, deserializedValue]);
+  }
+
+  return deserializedKeyValueList;
+}
+
+/**
+ * Deserialize a local value.
+ *
+ * @see https://w3c.github.io/webdriver-bidi/#deserialize-local-value
+ *
+ * @param {Realm} realm
+ *     The Realm in which the value is deserialized.
+ * @param {Object} serializedValue
+ *     Value of any type to be deserialized.
+ *
+ * @return {Object} Deserialized representation of the value.
+ */
+export function deserialize(realm, serializedValue) {
+  const { handle, type, value } = serializedValue;
+
+  // With a handle present deserialize as remote reference.
+  if (handle !== undefined) {
+    lazy.assert.string(
+      handle,
+      `Expected "handle" to be a string, got ${handle}`
+    );
+
+    const object = realm.getObjectForHandle(handle);
+    if (!object) {
+      throw new lazy.error.InvalidArgumentError(
+        `Unable to find an object reference for "handle" ${handle}`
+      );
+    }
+
+    return object;
+  }
+
+  lazy.assert.string(type, `Expected "type" to be a string, got ${type}`);
+
+  // Primitive protocol values
+  switch (type) {
+    case "undefined":
+      return undefined;
+    case "null":
+      return null;
+    case "string":
+      lazy.assert.string(
+        value,
+        `Expected "value" to be a string, got ${value}`
+      );
+      return value;
+    case "number":
+      // If value is already a number return its value.
+      if (typeof value === "number") {
+        return value;
+      }
+
+      // Otherwise it has to be one of the special strings
+      lazy.assert.in(
+        value,
+        ["NaN", "-0", "Infinity", "-Infinity"],
+        `Expected "value" to be one of "NaN", "-0", "Infinity", "-Infinity", got ${value}`
+      );
+      return Number(value);
+    case "boolean":
+      lazy.assert.boolean(
+        value,
+        `Expected "value" to be a boolean, got ${value}`
+      );
+      return value;
+    case "bigint":
+      lazy.assert.string(
+        value,
+        `Expected "value" to be a string, got ${value}`
+      );
+      try {
+        return BigInt(value);
+      } catch (e) {
+        throw new lazy.error.InvalidArgumentError(
+          `Failed to deserialize value as BigInt: ${value}`
+        );
+      }
+
+    // Non-primitive protocol values
+    case "array":
+      const array = realm.cloneIntoRealm([]);
+      deserializeValueList(realm, value).forEach(v => array.push(v));
+      return array;
+    case "date":
+      // We want to support only Date Time String format,
+      // check if the value follows it.
+      checkDateTimeString(value);
+
+      return realm.cloneIntoRealm(new Date(value));
+    case "map":
+      const map = realm.cloneIntoRealm(new Map());
+      deserializeKeyValueList(realm, value).forEach(([k, v]) => map.set(k, v));
+      return map;
+    case "object":
+      const object = realm.cloneIntoRealm({});
+      deserializeKeyValueList(realm, value).forEach(
+        ([k, v]) => (object[k] = v)
+      );
+      return object;
+    case "regexp":
+      lazy.assert.object(
+        value,
+        `Expected "value" for RegExp to be an object, got ${value}`
+      );
+      const { pattern, flags } = value;
+      lazy.assert.string(
+        pattern,
+        `Expected "pattern" for RegExp to be a string, got ${pattern}`
+      );
+      if (flags !== undefined) {
+        lazy.assert.string(
+          flags,
+          `Expected "flags" for RegExp to be a string, got ${flags}`
+        );
+      }
+      try {
+        return realm.cloneIntoRealm(new RegExp(pattern, flags));
+      } catch (e) {
+        throw new lazy.error.InvalidArgumentError(
+          `Failed to deserialize value as RegExp: ${value}`
+        );
+      }
+    case "set":
+      const set = realm.cloneIntoRealm(new Set());
+      deserializeValueList(realm, value).forEach(v => set.add(v));
+      return set;
+  }
+
+  lazy.logger.warn(`Unsupported type for local value ${type}`);
+  return undefined;
+}
+
+/**
+ * Helper to retrieve the handle id for a given object, for the provided realm
+ * and ownership type.
+ *
+ * See https://w3c.github.io/webdriver-bidi/#handle-for-an-object
+ *
+ * @param {Realm} realm
+ *     The Realm from which comes the value being serialized.
+ * @param {OwnershipModel} ownershipType
+ *     The ownership model to use for this serialization.
+ * @param {Object} object
+ *     The object being serialized.
+ *
+ * @return {string} The unique handle id for the object. Will be null if the
+ *     Ownership type is "none".
+ */
+function getHandleForObject(realm, ownershipType, object) {
+  if (ownershipType === OwnershipModel.None) {
+    return null;
+  }
+  return realm.getHandleForObject(object);
+}
+
+/**
+ * Helper to serialize an Array-like object.
+ *
+ * @see https://w3c.github.io/webdriver-bidi/#serialize-an-array-like
+ *
+ * @param {string} production
+ *     Type of object
+ * @param {string} handleId
+ *     The unique id of the <var>value</var>.
+ * @param {boolean} knownObject
+ *     Indicates if the <var>value</var> has already been serialized.
+ * @param {Object} value
+ *     The Array-like object to serialize.
+ * @param {number|null} maxDepth
+ *     Depth of a serialization.
+ * @param {OwnershipModel} ownershipType
+ *     The ownership model to use for this serialization.
+ * @param {Map} serializationInternalMap
+ *     Map of internal ids.
+ * @param {Realm} realm
+ *     The Realm from which comes the value being serialized.
+ *
+ * @return {Object} Object for serialized values.
+ */
+function serializeArrayLike(
+  production,
+  handleId,
+  knownObject,
+  value,
+  maxDepth,
+  ownershipType,
+  serializationInternalMap,
+  realm
+) {
+  const serialized = buildSerialized(production, handleId);
+  setInternalIdsIfNeeded(serializationInternalMap, serialized, value);
+
+  if (!knownObject && maxDepth !== null && maxDepth > 0) {
+    serialized.value = serializeList(
+      value,
+      maxDepth,
+      ownershipType,
+      serializationInternalMap,
+      realm
+    );
+  }
+
+  return serialized;
+}
+
+/**
+ * Helper to serialize as a list.
+ *
+ * @see https://w3c.github.io/webdriver-bidi/#serialize-as-a-list
+ *
+ * @param {Iterable} iterable
+ *     List of values to be serialized.
+ * @param {number|null} maxDepth
+ *     Depth of a serialization.
+ * @param {OwnershipModel} ownershipType
+ *     The ownership model to use for this serialization.
+ * @param {Map} serializationInternalMap
+ *     Map of internal ids.
+ * @param {Realm} realm
+ *     The Realm from which comes the value being serialized.
+ *
+ * @return {Array} List of serialized values.
+ */
+function serializeList(
+  iterable,
+  maxDepth,
+  ownershipType,
+  serializationInternalMap,
+  realm
+) {
+  const serialized = [];
+  const childDepth = maxDepth !== null ? maxDepth - 1 : null;
+
+  for (const item of iterable) {
+    serialized.push(
+      serialize(
+        item,
+        childDepth,
+        ownershipType,
+        serializationInternalMap,
+        realm
+      )
+    );
+  }
+
+  return serialized;
+}
+
+/**
+ * Helper to serialize as a mapping.
+ *
+ * @see https://w3c.github.io/webdriver-bidi/#serialize-as-a-mapping
+ *
+ * @param {Iterable} iterable
+ *     List of values to be serialized.
+ * @param {number|null} maxDepth
+ *     Depth of a serialization.
+ * @param {OwnershipModel} ownershipType
+ *     The ownership model to use for this serialization.
+ * @param {Map} serializationInternalMap
+ *     Map of internal ids.
+ * @param {Realm} realm
+ *     The Realm from which comes the value being serialized.
+ *
+ * @return {Array} List of serialized values.
+ */
+function serializeMapping(
+  iterable,
+  maxDepth,
+  ownershipType,
+  serializationInternalMap,
+  realm
+) {
+  const serialized = [];
+  const childDepth = maxDepth !== null ? maxDepth - 1 : null;
+
+  for (const [key, item] of iterable) {
+    const serializedKey =
+      typeof key == "string"
+        ? key
+        : serialize(
+            key,
+            childDepth,
+            ownershipType,
+            serializationInternalMap,
+            realm
+          );
+    const serializedValue = serialize(
+      item,
+      childDepth,
+      ownershipType,
+      serializationInternalMap,
+      realm
+    );
+
+    serialized.push([serializedKey, serializedValue]);
+  }
+
+  return serialized;
+}
+
+/**
+ * Helper to serialize as a Node.
+ *
+ * @param {Node} node
+ *     Node to be serialized.
+ * @param {number|null} maxDepth
+ *     Depth of a serialization.
+ * @param {OwnershipModel} ownershipType
+ *     The ownership model to use for this serialization.
+ * @param {Map} serializationInternalMap
+ *     Map of internal ids.
+ * @param {Realm} realm
+ *     The Realm from which comes the value being serialized.
+ *
+ * @return {Object} Serialized value.
+ */
+function serializeNode(
+  node,
+  maxDepth,
+  ownershipType,
+  serializationInternalMap,
+  realm
+) {
+  const isAttribute = Attr.isInstance(node);
+  const isElement = Element.isInstance(node);
+
+  const serialized = {
+    nodeType: node.nodeType,
+  };
+
+  if (node.nodeValue !== null) {
+    serialized.nodeValue = node.nodeValue;
+  }
+
+  if (isElement || isAttribute) {
+    serialized.localName = node.localName;
+    serialized.namespaceURI = node.namespaceURI;
+  }
+
+  serialized.childNodeCount = node.childNodes.length;
+
+  let children = null;
+  if (maxDepth !== 0) {
+    children = [];
+    const childDepth = maxDepth !== null ? maxDepth - 1 : null;
+    for (const child of node.childNodes) {
+      children.push(
+        serialize(
+          child,
+          childDepth,
+          ownershipType,
+          serializationInternalMap,
+          realm
+        )
+      );
+    }
+  }
+  serialized.children = children;
+
+  if (isElement) {
+    serialized.attributes = [...node.attributes].reduce((map, attr) => {
+      map[attr.name] = attr.value;
+      return map;
+    }, {});
+
+    // TODO: Bug 1802137 - Add support for shadowRoot
+  }
+
+  return serialized;
+}
+
+/**
+ * Serialize a value as a remote value.
+ *
+ * @see https://w3c.github.io/webdriver-bidi/#serialize-as-a-remote-value
+ *
+ * @param {Object} value
+ *     Value of any type to be serialized.
+ * @param {number|null} maxDepth
+ *     Depth of a serialization.
+ * @param {OwnershipModel} ownershipType
+ *     The ownership model to use for this serialization.
+ * @param {Map} serializationInternalMap
+ *     Map of internal ids.
+ * @param {Realm} realm
+ *     The Realm from which comes the value being serialized.
+ *
+ * @return {Object} Serialized representation of the value.
+ */
+export function serialize(
+  value,
+  maxDepth,
+  ownershipType,
+  serializationInternalMap,
+  realm
+) {
+  const type = typeof value;
+
+  // Primitive protocol values
+  if (type == "undefined") {
+    return { type };
+  } else if (Object.is(value, null)) {
+    return { type: "null" };
+  } else if (Object.is(value, NaN)) {
+    return { type: "number", value: "NaN" };
+  } else if (Object.is(value, -0)) {
+    return { type: "number", value: "-0" };
+  } else if (Object.is(value, Infinity)) {
+    return { type: "number", value: "Infinity" };
+  } else if (Object.is(value, -Infinity)) {
+    return { type: "number", value: "-Infinity" };
+  } else if (type == "bigint") {
+    return { type, value: value.toString() };
+  } else if (["boolean", "number", "string"].includes(type)) {
+    return { type, value };
+  }
+
+  const handleId = getHandleForObject(realm, ownershipType, value);
+  const knownObject = serializationInternalMap.has(value);
+
+  // Set the OwnershipModel to use for all complex object serializations.
+  ownershipType = OwnershipModel.None;
+
+  // Remote values
+
+  // symbols are primitive JS values which can only be serialized
+  // as remote values.
+  if (type == "symbol") {
+    return buildSerialized("symbol", handleId);
+  }
+
+  // All other remote values are non-primitives and their
+  // className can be extracted with ChromeUtils.getClassName
+  const className = ChromeUtils.getClassName(value);
+  if (["Array", "HTMLCollection", "NodeList"].includes(className)) {
+    return serializeArrayLike(
+      className.toLowerCase(),
+      handleId,
+      knownObject,
+      value,
+      maxDepth,
+      ownershipType,
+      serializationInternalMap,
+      realm
+    );
+  } else if (className == "RegExp") {
+    const serialized = buildSerialized("regexp", handleId);
+    serialized.value = { pattern: value.source, flags: value.flags };
+    return serialized;
+  } else if (className == "Date") {
+    const serialized = buildSerialized("date", handleId);
+    serialized.value = value.toISOString();
+    return serialized;
+  } else if (className == "Map") {
+    const serialized = buildSerialized("map", handleId);
+    setInternalIdsIfNeeded(serializationInternalMap, serialized, value);
+
+    if (!knownObject && maxDepth !== null && maxDepth > 0) {
+      serialized.value = serializeMapping(
+        value.entries(),
+        maxDepth,
+        ownershipType,
+        serializationInternalMap,
+        realm
+      );
+    }
+    return serialized;
+  } else if (className == "Set") {
+    const serialized = buildSerialized("set", handleId);
+    setInternalIdsIfNeeded(serializationInternalMap, serialized, value);
+
+    if (!knownObject && maxDepth !== null && maxDepth > 0) {
+      serialized.value = serializeList(
+        value.values(),
+        maxDepth,
+        ownershipType,
+        serializationInternalMap,
+        realm
+      );
+    }
+    return serialized;
+  } else if (
+    [
+      "ArrayBuffer",
+      "Function",
+      "Promise",
+      "WeakMap",
+      "WeakSet",
+      "Window",
+    ].includes(className)
+  ) {
+    return buildSerialized(className.toLowerCase(), handleId);
+  } else if (lazy.error.isError(value)) {
+    return buildSerialized("error", handleId);
+  } else if (TYPED_ARRAY_CLASSES.includes(className)) {
+    return buildSerialized("typedarray", handleId);
+  } else if (Node.isInstance(value)) {
+    const serialized = buildSerialized("node", handleId);
+    setInternalIdsIfNeeded(serializationInternalMap, serialized, value);
+
+    if (!knownObject) {
+      serialized.value = serializeNode(
+        value,
+        maxDepth,
+        ownershipType,
+        serializationInternalMap,
+        realm
+      );
+    }
+
+    return serialized;
+  } else if (ChromeUtils.isDOMObject(value)) {
+    const serialized = buildSerialized("object", handleId);
+    return serialized;
+  }
+
+  // Otherwise serialize the JavaScript object as generic object.
+  const serialized = buildSerialized("object", handleId);
+  setInternalIdsIfNeeded(serializationInternalMap, serialized, value);
+
+  if (!knownObject && maxDepth !== null && maxDepth > 0) {
+    serialized.value = serializeMapping(
+      Object.entries(value),
+      maxDepth,
+      ownershipType,
+      serializationInternalMap,
+      realm
+    );
+  }
+  return serialized;
+}
+
+/**
+ * Set the internalId property of a provided serialized RemoteValue,
+ * and potentially of a previously created serialized RemoteValue,
+ * corresponding to the same provided object.
+ *
+ * @see https://w3c.github.io/webdriver-bidi/#set-internal-ids-if-needed
+ *
+ * @param {Map} serializationInternalMap
+ *     Map of objects to remote values.
+ * @param {Object} remoteValue
+ *     A serialized RemoteValue for the provided object.
+ * @param {Object} object
+ *     Object of any type to be serialized.
+ */
+function setInternalIdsIfNeeded(serializationInternalMap, remoteValue, object) {
+  if (!serializationInternalMap.has(object)) {
+    // If the object was not tracked yet in the current serialization, add
+    // a new entry in the serialization internal map. An internal id will only
+    // be generated if the same object is encountered again.
+    serializationInternalMap.set(object, remoteValue);
+  } else {
+    // This is at least the second time this object is encountered, retrieve the
+    // original remote value stored for this object.
+    const previousRemoteValue = serializationInternalMap.get(object);
+
+    if (!previousRemoteValue.internalId) {
+      // If the original remote value has no internal id yet, generate a uuid
+      // and update the internalId of the original remote value with it.
+      previousRemoteValue.internalId = getUUID();
+    }
+
+    // Copy the internalId of the original remote value to the new remote value.
+    remoteValue.internalId = previousRemoteValue.internalId;
+  }
+}
+
+/**
+ * Safely stringify a value.
+ *
+ * @param {Object} value
+ *     Value of any type to be stringified.
+ *
+ * @return {string} String representation of the value.
+ */
+export function stringify(obj) {
+  let text;
+  try {
+    text =
+      obj !== null && typeof obj === "object" ? obj.toString() : String(obj);
+  } catch (e) {
+    // The error-case will also be handled in `finally {}`.
+  } finally {
+    if (typeof text != "string") {
+      text = Object.prototype.toString.apply(obj);
+    }
+  }
+
+  return text;
+}
diff --git a/remote/webdriver-bidi/WebDriverBiDi.sys.mjs b/remote/webdriver-bidi/WebDriverBiDi.sys.mjs
new file mode 100644
index 0000000000..a00e9c5788
--- /dev/null
+++ b/remote/webdriver-bidi/WebDriverBiDi.sys.mjs
@@ -0,0 +1,240 @@
+/* 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/. */
+
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  error: "chrome://remote/content/shared/webdriver/Errors.sys.mjs",
+  Log: "chrome://remote/content/shared/Log.sys.mjs",
+  WebDriverNewSessionHandler:
+    "chrome://remote/content/webdriver-bidi/NewSessionHandler.sys.mjs",
+  WebDriverSession: "chrome://remote/content/shared/webdriver/Session.sys.mjs",
+});
+
+XPCOMUtils.defineLazyGetter(lazy, "logger", () =>
+  lazy.Log.get(lazy.Log.TYPES.WEBDRIVER_BIDI)
+);
+XPCOMUtils.defineLazyGetter(lazy, "textEncoder", () => new TextEncoder());
+
+/**
+ * Entry class for the WebDriver BiDi support.
+ *
+ * @see https://w3c.github.io/webdriver-bidi
+ */
+export class WebDriverBiDi {
+  /**
+   * Creates a new instance of the WebDriverBiDi class.
+   *
+   * @param {RemoteAgent} agent
+   *     Reference to the Remote Agent instance.
+   */
+  constructor(agent) {
+    this.agent = agent;
+    this._running = false;
+
+    this._session = null;
+    this._sessionlessConnections = new Set();
+  }
+
+  get address() {
+    return `ws://${this.agent.host}:${this.agent.port}`;
+  }
+
+  get session() {
+    return this._session;
+  }
+
+  /**
+   * Add a new connection that is not yet attached to a WebDriver session.
+   *
+   * @param {WebDriverBiDiConnection} connection
+   *     The connection without an accociated WebDriver session.
+   */
+  addSessionlessConnection(connection) {
+    this._sessionlessConnections.add(connection);
+  }
+
+  /**
+   * Create a new WebDriver session.
+   *
+   * @param {Object.<string, *>=} capabilities
+   *     JSON Object containing any of the recognised capabilities as listed
+   *     on the `WebDriverSession` class.
+   *
+   * @param {WebDriverBiDiConnection=} sessionlessConnection
+   *     Optional connection that is not yet accociated with a WebDriver
+   *     session, and has to be associated with the new WebDriver session.
+   *
+   * @return {Object<String, Capabilities>}
+   *     Object containing the current session ID, and all its capabilities.
+   *
+   * @throws {SessionNotCreatedError}
+   *     If, for whatever reason, a session could not be created.
+   */
+  async createSession(capabilities, sessionlessConnection) {
+    if (this.session) {
+      throw new lazy.error.SessionNotCreatedError(
+        "Maximum number of active sessions"
+      );
+    }
+
+    const session = new lazy.WebDriverSession(
+      capabilities,
+      sessionlessConnection
+    );
+
+    // When the Remote Agent is listening, and a BiDi WebSocket connection
+    // has been requested, register a path handler for the session.
+    let webSocketUrl = null;
+    if (
+      this.agent.running &&
+      (session.capabilities.get("webSocketUrl") || sessionlessConnection)
+    ) {
+      // Creating a WebDriver BiDi session too early can cause issues with
+      // clients in not being able to find any available browsing context.
+      // Also when closing the application while it's still starting up can
+      // cause shutdown hangs. As such WebDriver BiDi will return a new session
+      // once the initial application window has finished initializing.
+      lazy.logger.debug(`Waiting for initial application window`);
+      await this.agent.browserStartupFinished;
+
+      this.agent.server.registerPathHandler(session.path, session);
+      webSocketUrl = `${this.address}${session.path}`;
+
+      lazy.logger.debug(`Registered session handler: ${session.path}`);
+
+      if (sessionlessConnection) {
+        // Remove temporary session-less connection
+        this._sessionlessConnections.delete(sessionlessConnection);
+      }
+    }
+
+    // Also update the webSocketUrl capability to contain the session URL if
+    // a path handler has been registered. Otherwise set its value to null.
+    session.capabilities.set("webSocketUrl", webSocketUrl);
+
+    this._session = session;
+
+    return {
+      sessionId: this.session.id,
+      capabilities: this.session.capabilities,
+    };
+  }
+
+  /**
+   * Delete the current WebDriver session.
+   */
+  deleteSession() {
+    if (!this.session) {
+      return;
+    }
+
+    // When the Remote Agent is listening, and a BiDi WebSocket is active,
+    // unregister the path handler for the session.
+    if (this.agent.running && this.session.capabilities.get("webSocketUrl")) {
+      this.agent.server.registerPathHandler(this.session.path, null);
+      lazy.logger.debug(`Unregistered session handler: ${this.session.path}`);
+    }
+
+    this.session.destroy();
+    this._session = null;
+  }
+
+  /**
+   * Retrieve the readiness state of the remote end, regarding the creation of
+   * new WebDriverBiDi sessions.
+   *
+   * See https://w3c.github.io/webdriver-bidi/#command-session-status
+   *
+   * @return {Object}
+   *     The readiness state.
+   */
+  getSessionReadinessStatus() {
+    if (this.session) {
+      // We currently only support one session, see Bug 1720707.
+      return {
+        ready: false,
+        message: "Session already started",
+      };
+    }
+
+    return {
+      ready: true,
+      message: "",
+    };
+  }
+
+  /**
+   * Starts the WebDriver BiDi support.
+   */
+  async start() {
+    if (this._running) {
+      return;
+    }
+
+    this._running = true;
+
+    // Install a HTTP handler for direct WebDriver BiDi connection requests.
+    this.agent.server.registerPathHandler(
+      "/session",
+      new lazy.WebDriverNewSessionHandler(this)
+    );
+
+    Cu.printStderr(`WebDriver BiDi listening on ${this.address}\n`);
+
+    // Write WebSocket connection details to the WebDriverBiDiServer.json file
+    // located within the application's profile.
+    this._bidiServerPath = PathUtils.join(
+      PathUtils.profileDir,
+      "WebDriverBiDiServer.json"
+    );
+
+    const data = {
+      ws_host: this.agent.host,
+      ws_port: this.agent.port,
+    };
+
+    try {
+      await IOUtils.write(
+        this._bidiServerPath,
+        lazy.textEncoder.encode(JSON.stringify(data, undefined, "  "))
+      );
+    } catch (e) {
+      lazy.logger.warn(
+        `Failed to create ${this._bidiServerPath} (${e.message})`
+      );
+    }
+  }
+
+  /**
+   * Stops the WebDriver BiDi support.
+   */
+  async stop() {
+    if (!this._running) {
+      return;
+    }
+
+    try {
+      try {
+        await IOUtils.remove(this._bidiServerPath);
+      } catch (e) {
+        lazy.logger.warn(
+          `Failed to remove ${this._bidiServerPath} (${e.message})`
+        );
+      }
+
+      this.deleteSession();
+
+      this.agent.server.registerPathHandler("/session", null);
+
+      // Close all open session-less connections
+      this._sessionlessConnections.forEach(connection => connection.close());
+      this._sessionlessConnections.clear();
+    } finally {
+      this._running = false;
+    }
+  }
+}
diff --git a/remote/webdriver-bidi/WebDriverBiDiConnection.sys.mjs b/remote/webdriver-bidi/WebDriverBiDiConnection.sys.mjs
new file mode 100644
index 0000000000..07819c775a
--- /dev/null
+++ b/remote/webdriver-bidi/WebDriverBiDiConnection.sys.mjs
@@ -0,0 +1,200 @@
+/* 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/. */
+
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
+
+import { WebSocketConnection } from "chrome://remote/content/shared/WebSocketConnection.sys.mjs";
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  assert: "chrome://remote/content/shared/webdriver/Assert.sys.mjs",
+  error: "chrome://remote/content/shared/webdriver/Errors.sys.mjs",
+  Log: "chrome://remote/content/shared/Log.sys.mjs",
+  RemoteAgent: "chrome://remote/content/components/RemoteAgent.sys.mjs",
+});
+
+XPCOMUtils.defineLazyGetter(lazy, "logger", () =>
+  lazy.Log.get(lazy.Log.TYPES.WEBDRIVER_BIDI)
+);
+
+export class WebDriverBiDiConnection extends WebSocketConnection {
+  /**
+   * @param {WebSocket} webSocket
+   *     The WebSocket server connection to wrap.
+   * @param {Connection} httpdConnection
+   *     Reference to the httpd.js's connection needed for clean-up.
+   */
+  constructor(webSocket, httpdConnection) {
+    super(webSocket, httpdConnection);
+
+    // Each connection has only a single associated WebDriver session.
+    this.session = null;
+  }
+
+  /**
+   * Register a new WebDriver Session to forward the messages to.
+   *
+   * @param {Session} session
+   *     The WebDriverSession to register.
+   */
+  registerSession(session) {
+    if (this.session) {
+      throw new lazy.error.UnknownError(
+        "A WebDriver session has already been set"
+      );
+    }
+
+    this.session = session;
+    lazy.logger.debug(
+      `Connection ${this.id} attached to session ${session.id}`
+    );
+  }
+
+  /**
+   * Unregister the already set WebDriver session.
+   *
+   * @param {Session} session
+   *     The WebDriverSession to register.
+   */
+  unregisterSession() {
+    if (!this.session) {
+      return;
+    }
+
+    this.session.removeConnection(this);
+    this.session = null;
+  }
+
+  /**
+   * Send an error back to the WebDriver BiDi client.
+   *
+   * @param {Number} id
+   *     Id of the packet which lead to an error.
+   * @param {Error} err
+   *     Error object with `status`, `message` and `stack` attributes.
+   */
+  sendError(id, err) {
+    const webDriverError = lazy.error.wrap(err);
+
+    this.send({
+      id,
+      error: webDriverError.status,
+      message: webDriverError.message,
+      stacktrace: webDriverError.stack,
+    });
+  }
+
+  /**
+   * Send an event coming from a module to the WebDriver BiDi client.
+   *
+   * @param {String} method
+   *     The event name. This is composed by a module name, a dot character
+   *     followed by the event name, e.g. `log.entryAdded`.
+   * @param {Object} params
+   *     A JSON-serializable object, which is the payload of this event.
+   */
+  sendEvent(method, params) {
+    this.send({ method, params });
+  }
+
+  /**
+   * Send the result of a call to a module's method back to the
+   * WebDriver BiDi client.
+   *
+   * @param {Number} id
+   *     The request id being sent by the client to call the module's method.
+   * @param {Object} result
+   *     A JSON-serializable object, which is the actual result.
+   */
+  sendResult(id, result) {
+    result = typeof result !== "undefined" ? result : {};
+    this.send({ id, result });
+  }
+
+  // Transport hooks
+
+  /**
+   * Called by the `transport` when the connection is closed.
+   */
+  onClosed() {
+    this.unregisterSession();
+
+    super.onClosed();
+  }
+
+  /**
+   * Receive a packet from the WebSocket layer.
+   *
+   * This packet is sent by a WebDriver BiDi client and is meant to execute
+   * a particular method on a given module.
+   *
+   * @param Object packet
+   *        JSON-serializable object sent by the client
+   */
+  async onPacket(packet) {
+    super.onPacket(packet);
+
+    const { id, method, params } = packet;
+
+    try {
+      // First check for mandatory field in the command packet
+      lazy.assert.positiveInteger(id, "id: unsigned integer value expected");
+      lazy.assert.string(method, "method: string value expected");
+      lazy.assert.object(params, "params: object value expected");
+
+      // Extract the module and the command name out of `method` attribute
+      const { module, command } = splitMethod(method);
+      let result;
+
+      // Handle static commands first
+      if (module === "session" && command === "new") {
+        // TODO: Needs capability matching code
+        result = await lazy.RemoteAgent.webDriverBiDi.createSession(
+          params,
+          this
+        );
+      } else if (module === "session" && command === "status") {
+        result = lazy.RemoteAgent.webDriverBiDi.getSessionReadinessStatus();
+      } else {
+        lazy.assert.session(this.session);
+
+        // Bug 1741854 - Workaround to deny internal methods to be called
+        if (command.startsWith("_")) {
+          throw new lazy.error.UnknownCommandError(method);
+        }
+
+        // Finally, instruct the session to execute the command
+        result = await this.session.execute(module, command, params);
+      }
+
+      this.sendResult(id, result);
+    } catch (e) {
+      this.sendError(packet.id, e);
+    }
+  }
+}
+
+/**
+ * Splits a WebDriver BiDi method into module and command components.
+ *
+ * @param {String} method
+ *     Name of the method to split, e.g. "session.subscribe".
+ *
+ * @returns {Object<String, String>}
+ *     Object with the module ("session") and command ("subscribe")
+ *     as properties.
+ */
+export function splitMethod(method) {
+  const parts = method.split(".");
+
+  if (parts.length != 2 || !parts[0].length || !parts[1].length) {
+    throw new TypeError(`Invalid method format: '${method}'`);
+  }
+
+  return {
+    module: parts[0],
+    command: parts[1],
+  };
+}
diff --git a/remote/webdriver-bidi/jar.mn b/remote/webdriver-bidi/jar.mn
new file mode 100644
index 0000000000..44fc24c56f
--- /dev/null
+++ b/remote/webdriver-bidi/jar.mn
@@ -0,0 +1,31 @@
+# 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/.
+
+remote.jar:
+% content remote %content/
+
+  content/webdriver-bidi/NewSessionHandler.sys.mjs (NewSessionHandler.sys.mjs)
+  content/webdriver-bidi/Realm.sys.mjs (Realm.sys.mjs)
+  content/webdriver-bidi/RemoteValue.sys.mjs (RemoteValue.sys.mjs)
+  content/webdriver-bidi/WebDriverBiDi.sys.mjs (WebDriverBiDi.sys.mjs)
+  content/webdriver-bidi/WebDriverBiDiConnection.sys.mjs (WebDriverBiDiConnection.sys.mjs)
+
+  # WebDriver BiDi modules
+  content/webdriver-bidi/modules/ModuleRegistry.sys.mjs (modules/ModuleRegistry.sys.mjs)
+
+  # WebDriver BiDi root modules
+  content/webdriver-bidi/modules/root/browsingContext.sys.mjs (modules/root/browsingContext.sys.mjs)
+  content/webdriver-bidi/modules/root/log.sys.mjs (modules/root/log.sys.mjs)
+  content/webdriver-bidi/modules/root/network.sys.mjs (modules/root/network.sys.mjs)
+  content/webdriver-bidi/modules/root/script.sys.mjs (modules/root/script.sys.mjs)
+  content/webdriver-bidi/modules/root/session.sys.mjs (modules/root/session.sys.mjs)
+
+  # WebDriver BiDi windowglobal modules
+  content/webdriver-bidi/modules/windowglobal/browsingContext.sys.mjs (modules/windowglobal/browsingContext.sys.mjs)
+  content/webdriver-bidi/modules/windowglobal/log.sys.mjs (modules/windowglobal/log.sys.mjs)
+  content/webdriver-bidi/modules/windowglobal/script.sys.mjs (modules/windowglobal/script.sys.mjs)
+
+  # WebDriver BiDi windowglobal-in-root modules
+  content/webdriver-bidi/modules/windowglobal-in-root/browsingContext.sys.mjs (modules/windowglobal-in-root/browsingContext.sys.mjs)
+  content/webdriver-bidi/modules/windowglobal-in-root/log.sys.mjs (modules/windowglobal-in-root/log.sys.mjs)
diff --git a/remote/webdriver-bidi/modules/ModuleRegistry.sys.mjs b/remote/webdriver-bidi/modules/ModuleRegistry.sys.mjs
new file mode 100644
index 0000000000..5bb1a908bf
--- /dev/null
+++ b/remote/webdriver-bidi/modules/ModuleRegistry.sys.mjs
@@ -0,0 +1,69 @@
+/* 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/. */
+
+const modules = {
+  root: {},
+  "windowglobal-in-root": {},
+  windowglobal: {},
+};
+
+// eslint-disable-next-line mozilla/lazy-getter-object-name
+ChromeUtils.defineESModuleGetters(modules.root, {
+  browsingContext:
+    "chrome://remote/content/webdriver-bidi/modules/root/browsingContext.sys.mjs",
+  log: "chrome://remote/content/webdriver-bidi/modules/root/log.sys.mjs",
+  network:
+    "chrome://remote/content/webdriver-bidi/modules/root/network.sys.mjs",
+  script: "chrome://remote/content/webdriver-bidi/modules/root/script.sys.mjs",
+  session:
+    "chrome://remote/content/webdriver-bidi/modules/root/session.sys.mjs",
+});
+
+// eslint-disable-next-line mozilla/lazy-getter-object-name
+ChromeUtils.defineESModuleGetters(modules["windowglobal-in-root"], {
+  browsingContext:
+    "chrome://remote/content/webdriver-bidi/modules/windowglobal-in-root/browsingContext.sys.mjs",
+  log:
+    "chrome://remote/content/webdriver-bidi/modules/windowglobal-in-root/log.sys.mjs",
+});
+
+// eslint-disable-next-line mozilla/lazy-getter-object-name
+ChromeUtils.defineESModuleGetters(modules.windowglobal, {
+  browsingContext:
+    "chrome://remote/content/webdriver-bidi/modules/windowglobal/browsingContext.sys.mjs",
+  log:
+    "chrome://remote/content/webdriver-bidi/modules/windowglobal/log.sys.mjs",
+  script:
+    "chrome://remote/content/webdriver-bidi/modules/windowglobal/script.sys.mjs",
+});
+
+/**
+ * Retrieve the WebDriver BiDi module class matching the provided module name
+ * and folder.
+ *
+ * @param {String} moduleName
+ *     The name of the module to get the class for.
+ * @param {String} moduleFolder
+ *     A valid folder name for modules.
+ * @return {Class=}
+ *     The class corresponding to the module name and folder, null if no match
+ *     was found.
+ * @throws {Error}
+ *     If the provided module folder is unexpected.
+ **/
+export const getModuleClass = function(moduleName, moduleFolder) {
+  if (!modules[moduleFolder]) {
+    throw new Error(
+      `Invalid module folder "${moduleFolder}", expected one of "${Object.keys(
+        modules
+      )}"`
+    );
+  }
+
+  if (!modules[moduleFolder][moduleName]) {
+    return null;
+  }
+
+  return modules[moduleFolder][moduleName];
+};
diff --git a/remote/webdriver-bidi/modules/root/browsingContext.sys.mjs b/remote/webdriver-bidi/modules/root/browsingContext.sys.mjs
new file mode 100644
index 0000000000..cd8dff6ca0
--- /dev/null
+++ b/remote/webdriver-bidi/modules/root/browsingContext.sys.mjs
@@ -0,0 +1,663 @@
+/* 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/. */
+
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
+
+import { Module } from "chrome://remote/content/shared/messagehandler/Module.sys.mjs";
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  AppInfo: "chrome://remote/content/shared/AppInfo.sys.mjs",
+  assert: "chrome://remote/content/shared/webdriver/Assert.sys.mjs",
+  BrowsingContextListener:
+    "chrome://remote/content/shared/listeners/BrowsingContextListener.sys.mjs",
+  capture: "chrome://remote/content/shared/Capture.sys.mjs",
+  ContextDescriptorType:
+    "chrome://remote/content/shared/messagehandler/MessageHandler.sys.mjs",
+  error: "chrome://remote/content/shared/webdriver/Errors.sys.mjs",
+  Log: "chrome://remote/content/shared/Log.sys.mjs",
+  pprint: "chrome://remote/content/shared/Format.sys.mjs",
+  ProgressListener: "chrome://remote/content/shared/Navigate.sys.mjs",
+  TabManager: "chrome://remote/content/shared/TabManager.sys.mjs",
+  waitForInitialNavigationCompleted:
+    "chrome://remote/content/shared/Navigate.sys.mjs",
+  WindowGlobalMessageHandler:
+    "chrome://remote/content/shared/messagehandler/WindowGlobalMessageHandler.sys.mjs",
+  windowManager: "chrome://remote/content/shared/WindowManager.sys.mjs",
+});
+
+XPCOMUtils.defineLazyGetter(lazy, "logger", () =>
+  lazy.Log.get(lazy.Log.TYPES.WEBDRIVER_BIDI)
+);
+
+/**
+ * @typedef {Object} CreateType
+ **/
+
+/**
+ * Enum of types supported by the browsingContext.create command.
+ *
+ * @readonly
+ * @enum {CreateType}
+ **/
+const CreateType = {
+  tab: "tab",
+  window: "window",
+};
+
+/**
+ * @typedef {string} WaitCondition
+ **/
+
+/**
+ * Wait conditions supported by WebDriver BiDi for navigation.
+ *
+ * @enum {WaitCondition}
+ */
+const WaitCondition = {
+  None: "none",
+  Interactive: "interactive",
+  Complete: "complete",
+};
+
+class BrowsingContextModule extends Module {
+  #contextListener;
+  #subscribedEvents;
+
+  /**
+   * Create a new module instance.
+   *
+   * @param {MessageHandler} messageHandler
+   *     The MessageHandler instance which owns this Module instance.
+   */
+  constructor(messageHandler) {
+    super(messageHandler);
+
+    // Create the console-api listener and listen on "message" events.
+    this.#contextListener = new lazy.BrowsingContextListener();
+    this.#contextListener.on("attached", this.#onContextAttached);
+
+    // Set of event names which have active subscriptions.
+    this.#subscribedEvents = new Set();
+  }
+
+  destroy() {
+    this.#contextListener.off("attached", this.#onContextAttached);
+    this.#contextListener.destroy();
+
+    this.#subscribedEvents = null;
+  }
+
+  /**
+   * Capture a base64-encoded screenshot of the provided browsing context.
+   *
+   * @param {Object=} options
+   * @param {string} context
+   *     Id of the browsing context to screenshot.
+   *
+   * @throws {NoSuchFrameError}
+   *     If the browsing context cannot be found.
+   */
+  async captureScreenshot(options = {}) {
+    const { context: contextId } = options;
+
+    lazy.assert.string(
+      contextId,
+      `Expected "context" to be a string, got ${contextId}`
+    );
+    const context = this.#getBrowsingContext(contextId);
+
+    const rect = await this.messageHandler.handleCommand({
+      moduleName: "browsingContext",
+      commandName: "_getScreenshotRect",
+      destination: {
+        type: lazy.WindowGlobalMessageHandler.type,
+        id: context.id,
+      },
+      retryOnAbort: true,
+    });
+
+    const canvas = await lazy.capture.canvas(
+      context.topChromeWindow,
+      context,
+      rect.x,
+      rect.y,
+      rect.width,
+      rect.height
+    );
+
+    return {
+      data: lazy.capture.toBase64(canvas),
+    };
+  }
+
+  /**
+   * Close the provided browsing context.
+   *
+   * @param {Object=} options
+   * @param {string} context
+   *     Id of the browsing context to close.
+   *
+   * @throws {NoSuchFrameError}
+   *     If the browsing context cannot be found.
+   * @throws {InvalidArgumentError}
+   *     If the browsing context is not a top-level one.
+   */
+  async close(options = {}) {
+    const { context: contextId } = options;
+
+    lazy.assert.string(
+      contextId,
+      `Expected "context" to be a string, got ${contextId}`
+    );
+
+    const context = lazy.TabManager.getBrowsingContextById(contextId);
+    if (!context) {
+      throw new lazy.error.NoSuchFrameError(
+        `Browsing Context with id ${contextId} not found`
+      );
+    }
+
+    if (context.parent) {
+      throw new lazy.error.InvalidArgumentError(
+        `Browsing Context with id ${contextId} is not top-level`
+      );
+    }
+
+    if (lazy.TabManager.getTabCount() === 1) {
+      // The behavior when closing the last tab is currently unspecified.
+      // Warn the consumer about potential issues
+      lazy.logger.warn(
+        `Closing the last open tab (Browsing Context id ${contextId}), expect inconsistent behavior across platforms`
+      );
+    }
+
+    const tab = lazy.TabManager.getTabForBrowsingContext(context);
+    await lazy.TabManager.removeTab(tab);
+  }
+
+  /**
+   * Create a new browsing context using the provided type "tab" or "window".
+   *
+   * @param {Object=} options
+   * @param {string=} options.referenceContext
+   *     Id of the top-level browsing context to use as reference.
+   *     If options.type is "tab", the new tab will open in the same window as
+   *     the reference context, and will be added next to the reference context.
+   *     If options.type is "window", the reference context is ignored.
+   * @param {CreateType} options.type
+   *     Type of browsing context to create.
+   *
+   * @throws {InvalidArgumentError}
+   *     If the browsing context is not a top-level one.
+   * @throws {NoSuchFrameError}
+   *     If the browsing context cannot be found.
+   */
+  async create(options = {}) {
+    const { referenceContext: referenceContextId = null, type } = options;
+    if (type !== CreateType.tab && type !== CreateType.window) {
+      throw new lazy.error.InvalidArgumentError(
+        `Expected "type" to be one of ${Object.values(CreateType)}, got ${type}`
+      );
+    }
+
+    let browser;
+    switch (type) {
+      case "window":
+        let newWindow = await lazy.windowManager.openBrowserWindow();
+        browser = lazy.TabManager.getTabBrowser(newWindow).selectedBrowser;
+        break;
+
+      case "tab":
+        if (!lazy.TabManager.supportsTabs()) {
+          throw new lazy.error.UnsupportedOperationError(
+            `browsingContext.create with type "tab" not supported in ${lazy.AppInfo.name}`
+          );
+        }
+
+        let referenceTab;
+        if (referenceContextId !== null) {
+          lazy.assert.string(
+            referenceContextId,
+            lazy.pprint`Expected "referenceContext" to be a string, got ${referenceContextId}`
+          );
+
+          const referenceBrowsingContext = lazy.TabManager.getBrowsingContextById(
+            referenceContextId
+          );
+          if (!referenceBrowsingContext) {
+            throw new lazy.error.NoSuchFrameError(
+              `Browsing Context with id ${referenceContextId} not found`
+            );
+          }
+
+          if (referenceBrowsingContext.parent) {
+            throw new lazy.error.InvalidArgumentError(
+              `referenceContext with id ${referenceContextId} is not a top-level browsing context`
+            );
+          }
+
+          referenceTab = lazy.TabManager.getTabForBrowsingContext(
+            referenceBrowsingContext
+          );
+        }
+
+        const tab = await lazy.TabManager.addTab({
+          focus: false,
+          referenceTab,
+        });
+        browser = lazy.TabManager.getBrowserForTab(tab);
+    }
+
+    await lazy.waitForInitialNavigationCompleted(
+      browser.browsingContext.webProgress
+    );
+
+    return {
+      context: lazy.TabManager.getIdForBrowser(browser),
+    };
+  }
+
+  /**
+   * An object that holds the WebDriver Bidi browsing context information.
+   *
+   * @typedef BrowsingContextInfo
+   *
+   * @property {string} context
+   *     The id of the browsing context.
+   * @property {string=} parent
+   *     The parent of the browsing context if it's the root browsing context
+   *     of the to be processed browsing context tree.
+   * @property {string} url
+   *     The current documents location.
+   * @property {Array<BrowsingContextInfo>=} children
+   *     List of child browsing contexts. Only set if maxDepth hasn't been
+   *     reached yet.
+   */
+
+  /**
+   * An object that holds the WebDriver Bidi browsing context tree information.
+   *
+   * @typedef BrowsingContextGetTreeResult
+   *
+   * @property {Array<BrowsingContextInfo>} contexts
+   *     List of child browsing contexts.
+   */
+
+  /**
+   * Returns a tree of all browsing contexts that are descendents of the
+   * given context, or all top-level contexts when no root is provided.
+   *
+   * @param {Object=} options
+   * @param {number=} maxDepth
+   *     Depth of the browsing context tree to traverse. If not specified
+   *     the whole tree is returned.
+   * @param {string=} root
+   *     Id of the root browsing context.
+   *
+   * @returns {BrowsingContextGetTreeResult}
+   *     Tree of browsing context information.
+   * @throws {NoSuchFrameError}
+   *     If the browsing context cannot be found.
+   */
+  getTree(options = {}) {
+    const { maxDepth = null, root: rootId = null } = options;
+
+    if (maxDepth !== null) {
+      lazy.assert.positiveInteger(
+        maxDepth,
+        `Expected "maxDepth" to be a positive integer, got ${maxDepth}`
+      );
+    }
+
+    let contexts;
+    if (rootId !== null) {
+      // With a root id specified return the context info for itself
+      // and the full tree.
+      lazy.assert.string(
+        rootId,
+        `Expected "root" to be a string, got ${rootId}`
+      );
+      contexts = [this.#getBrowsingContext(rootId)];
+    } else {
+      // Return all top-level browsing contexts.
+      contexts = lazy.TabManager.browsers.map(
+        browser => browser.browsingContext
+      );
+    }
+
+    const contextsInfo = contexts.map(context => {
+      return this.#getBrowsingContextInfo(context, { maxDepth });
+    });
+
+    return { contexts: contextsInfo };
+  }
+
+  /**
+   * An object that holds the WebDriver Bidi navigation information.
+   *
+   * @typedef BrowsingContextNavigateResult
+   *
+   * @property {String} navigation
+   *     Unique id for this navigation.
+   * @property {String} url
+   *     The requested or reached URL.
+   */
+
+  /**
+   * Navigate the given context to the provided url, with the provided wait condition.
+   *
+   * @param {Object=} options
+   * @param {string} context
+   *     Id of the browsing context to navigate.
+   * @param {string} url
+   *     Url for the navigation.
+   * @param {WaitCondition=} wait
+   *     Wait condition for the navigation, one of "none", "interactive", "complete".
+   *
+   * @returns {BrowsingContextNavigateResult}
+   *     Navigation result.
+   * @throws {InvalidArgumentError}
+   *     Raised if an argument is of an invalid type or value.
+   * @throws {NoSuchFrameError}
+   *     If the browsing context for contextId cannot be found.
+   */
+  async navigate(options = {}) {
+    const { context: contextId, url, wait = WaitCondition.None } = options;
+
+    lazy.assert.string(
+      contextId,
+      `Expected "context" to be a string, got ${contextId}`
+    );
+
+    lazy.assert.string(url, `Expected "url" to be string, got ${url}`);
+
+    const waitConditions = Object.values(WaitCondition);
+    if (!waitConditions.includes(wait)) {
+      throw new lazy.error.InvalidArgumentError(
+        `Expected "wait" to be one of ${waitConditions}, got ${wait}`
+      );
+    }
+
+    const context = this.#getBrowsingContext(contextId);
+
+    // webProgress will be stable even if the context navigates, retrieve it
+    // immediately before doing any asynchronous call.
+    const webProgress = context.webProgress;
+
+    const base = await this.messageHandler.handleCommand({
+      moduleName: "browsingContext",
+      commandName: "_getBaseURL",
+      destination: {
+        type: lazy.WindowGlobalMessageHandler.type,
+        id: context.id,
+      },
+      retryOnAbort: true,
+    });
+
+    let targetURI;
+    try {
+      const baseURI = Services.io.newURI(base);
+      targetURI = Services.io.newURI(url, null, baseURI);
+    } catch (e) {
+      throw new lazy.error.InvalidArgumentError(
+        `Expected "url" to be a valid URL (${e.message})`
+      );
+    }
+
+    return this.#awaitNavigation(webProgress, targetURI, {
+      wait,
+    });
+  }
+
+  /**
+   * Start and await a navigation on the provided BrowsingContext. Returns a
+   * promise which resolves when the navigation is done according to the provided
+   * navigation strategy.
+   *
+   * @param {WebProgress} webProgress
+   *     The WebProgress instance to observe for this navigation.
+   * @param {nsIURI} targetURI
+   *     The URI to navigate to.
+   * @param {Object} options
+   * @param {WaitCondition} options.wait
+   *     The WaitCondition to use to wait for the navigation.
+   */
+  async #awaitNavigation(webProgress, targetURI, options) {
+    const { wait } = options;
+
+    const context = webProgress.browsingContext;
+    const browserId = context.browserId;
+
+    const resolveWhenStarted = wait === WaitCondition.None;
+    const listener = new lazy.ProgressListener(webProgress, {
+      expectNavigation: true,
+      resolveWhenStarted,
+      // In case the webprogress is already navigating, always wait for an
+      // explicit start flag.
+      waitForExplicitStart: true,
+    });
+
+    const onDocumentInteractive = (evtName, wrappedEvt) => {
+      if (webProgress.browsingContext.id !== wrappedEvt.contextId) {
+        // Ignore load events for unrelated browsing contexts.
+        return;
+      }
+
+      if (wrappedEvt.readyState === "interactive") {
+        listener.stopIfStarted();
+      }
+    };
+
+    const contextDescriptor = {
+      type: lazy.ContextDescriptorType.TopBrowsingContext,
+      id: browserId,
+    };
+
+    // For the Interactive wait condition, resolve as soon as
+    // the document becomes interactive.
+    if (wait === WaitCondition.Interactive) {
+      await this.messageHandler.eventsDispatcher.on(
+        "browsingContext._documentInteractive",
+        contextDescriptor,
+        onDocumentInteractive
+      );
+    }
+
+    const navigated = listener.start();
+    navigated.finally(async () => {
+      if (listener.isStarted) {
+        listener.stop();
+      }
+
+      if (wait === WaitCondition.Interactive) {
+        await this.messageHandler.eventsDispatcher.off(
+          "browsingContext._documentInteractive",
+          contextDescriptor,
+          onDocumentInteractive
+        );
+      }
+    });
+
+    context.loadURI(targetURI.spec, {
+      loadFlags: Ci.nsIWebNavigation.LOAD_FLAGS_IS_LINK,
+      triggeringPrincipal: Services.scriptSecurityManager.getSystemPrincipal(),
+      hasValidUserGestureActivation: true,
+    });
+    await navigated;
+
+    let url;
+    if (wait === WaitCondition.None) {
+      // If wait condition is None, the navigation resolved before the current
+      // context has navigated.
+      url = listener.targetURI.spec;
+    } else {
+      url = listener.currentURI.spec;
+    }
+
+    return {
+      // TODO: The navigation id should be a real id mapped to the navigation.
+      // See https://bugzilla.mozilla.org/show_bug.cgi?id=1763122
+      navigation: null,
+      url,
+    };
+  }
+
+  /**
+   * Retrieves a browsing context based on its id.
+   *
+   * @param {Number} contextId
+   *     Id of the browsing context.
+   * @returns {BrowsingContext=}
+   *     The browsing context or null if <var>contextId</var> is null.
+   * @throws {NoSuchFrameError}
+   *     If the browsing context cannot be found.
+   */
+  #getBrowsingContext(contextId) {
+    // The WebDriver BiDi specification expects null to be
+    // returned if no browsing context id has been specified.
+    if (contextId === null) {
+      return null;
+    }
+
+    const context = lazy.TabManager.getBrowsingContextById(contextId);
+    if (context === null) {
+      throw new lazy.error.NoSuchFrameError(
+        `Browsing Context with id ${contextId} not found`
+      );
+    }
+
+    return context;
+  }
+
+  /**
+   * Get the WebDriver BiDi browsing context information.
+   *
+   * @param {BrowsingContext} context
+   *     The browsing context to get the information from.
+   * @param {Object=} options
+   * @param {boolean=} isRoot
+   *     Flag that indicates if this browsing context is the root of all the
+   *     browsing contexts to be returned. Defaults to true.
+   * @param {number=} maxDepth
+   *     Depth of the browsing context tree to traverse. If not specified
+   *     the whole tree is returned.
+   * @returns {BrowsingContextInfo}
+   *     The information about the browsing context.
+   */
+  #getBrowsingContextInfo(context, options = {}) {
+    const { isRoot = true, maxDepth = null } = options;
+
+    let children = null;
+    if (maxDepth === null || maxDepth > 0) {
+      children = context.children.map(context =>
+        this.#getBrowsingContextInfo(context, {
+          maxDepth: maxDepth === null ? maxDepth : maxDepth - 1,
+          isRoot: false,
+        })
+      );
+    }
+
+    const contextInfo = {
+      context: lazy.TabManager.getIdForBrowsingContext(context),
+      url: context.currentURI.spec,
+      children,
+    };
+
+    if (isRoot) {
+      // Only emit the parent id for the top-most browsing context.
+      const parentId = lazy.TabManager.getIdForBrowsingContext(context.parent);
+      contextInfo.parent = parentId;
+    }
+
+    return contextInfo;
+  }
+
+  #onContextAttached = async (eventName, data = {}) => {
+    const { browsingContext, why } = data;
+
+    // Filter out top-level browsing contexts that are created because of a
+    // cross-group navigation.
+    if (why === "replace") {
+      return;
+    }
+
+    // Filter out notifications for chrome context until support gets
+    // added (bug 1722679).
+    if (!browsingContext.webProgress) {
+      return;
+    }
+
+    const browsingContextInfo = this.#getBrowsingContextInfo(browsingContext, {
+      maxDepth: 0,
+    });
+
+    // This event is emitted from the parent process but for a given browsing
+    // context. Set the event's contextInfo to the message handler corresponding
+    // to this browsing context.
+    const contextInfo = {
+      contextId: browsingContext.id,
+      type: lazy.WindowGlobalMessageHandler.type,
+    };
+    this.emitEvent(
+      "browsingContext.contextCreated",
+      browsingContextInfo,
+      contextInfo
+    );
+  };
+
+  #subscribeEvent(event) {
+    if (event === "browsingContext.contextCreated") {
+      this.#contextListener.startListening();
+      this.#subscribedEvents.add(event);
+    }
+  }
+
+  #unsubscribeEvent(event) {
+    if (event === "browsingContext.contextCreated") {
+      this.#contextListener.stopListening();
+      this.#subscribedEvents.delete(event);
+    }
+  }
+
+  /**
+   * Internal commands
+   */
+
+  _applySessionData(params) {
+    // TODO: Bug 1775231. Move this logic to a shared module or an abstract
+    // class.
+    const { category } = params;
+    if (category === "event") {
+      const filteredSessionData = params.sessionData.filter(item =>
+        this.messageHandler.matchesContext(item.contextDescriptor)
+      );
+      for (const event of this.#subscribedEvents.values()) {
+        const hasSessionItem = filteredSessionData.some(
+          item => item.value === event
+        );
+        // If there are no session items for this context, we should unsubscribe from the event.
+        if (!hasSessionItem) {
+          this.#unsubscribeEvent(event);
+        }
+      }
+
+      // Subscribe to all events, which have an item in SessionData.
+      for (const { value } of filteredSessionData) {
+        this.#subscribeEvent(value);
+      }
+    }
+  }
+
+  static get supportedEvents() {
+    return [
+      "browsingContext.contextCreated",
+      "browsingContext.domContentLoaded",
+      "browsingContext.load",
+    ];
+  }
+}
+
+export const browsingContext = BrowsingContextModule;
diff --git a/remote/webdriver-bidi/modules/root/log.sys.mjs b/remote/webdriver-bidi/modules/root/log.sys.mjs
new file mode 100644
index 0000000000..db2390d3ba
--- /dev/null
+++ b/remote/webdriver-bidi/modules/root/log.sys.mjs
@@ -0,0 +1,15 @@
+/* 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/. */
+
+import { Module } from "chrome://remote/content/shared/messagehandler/Module.sys.mjs";
+
+class LogModule extends Module {
+  destroy() {}
+
+  static get supportedEvents() {
+    return ["log.entryAdded"];
+  }
+}
+
+export const log = LogModule;
diff --git a/remote/webdriver-bidi/modules/root/network.sys.mjs b/remote/webdriver-bidi/modules/root/network.sys.mjs
new file mode 100644
index 0000000000..e82bc3c072
--- /dev/null
+++ b/remote/webdriver-bidi/modules/root/network.sys.mjs
@@ -0,0 +1,342 @@
+/* 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/. */
+
+import { Module } from "chrome://remote/content/shared/messagehandler/Module.sys.mjs";
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  error: "chrome://remote/content/shared/webdriver/Errors.sys.mjs",
+  NetworkListener:
+    "chrome://remote/content/shared/listeners/NetworkListener.sys.mjs",
+  TabManager: "chrome://remote/content/shared/TabManager.sys.mjs",
+  WindowGlobalMessageHandler:
+    "chrome://remote/content/shared/messagehandler/WindowGlobalMessageHandler.sys.mjs",
+});
+
+/**
+ * @typedef {Object} BaseParameters
+ * @property {string=} context
+ * @property {boolean} isRedirect
+ * @property {Navigation=} navigation
+ * @property {RequestData} request
+ * @property {number} timestamp
+ */
+
+/**
+ * @typedef {Object} Cookie
+ * @property {Array<number>=} binaryValue
+ * @property {string} domain
+ * @property {number=} expires
+ * @property {boolean} httpOnly
+ * @property {string} name
+ * @property {string} path
+ * @property {('lax' | 'none' | 'strict')} sameSite
+ * @property {boolean} secure
+ * @property {number} size
+ * @property {string=} value
+ */
+
+/**
+ * @typedef {Object} FetchTimingInfo
+ * @property {number} originTime
+ * @property {number} requestTime
+ * @property {number} redirectStart
+ * @property {number} redirectEnd
+ * @property {number} fetchStart
+ * @property {number} dnsStart
+ * @property {number} dnsEnd
+ * @property {number} connectStart
+ * @property {number} connectEnd
+ * @property {number} tlsStart
+ * @property {number} requestStart
+ * @property {number} responseStart
+ * @property {number} responseEnd
+ */
+
+/**
+ * @typedef {Object} Header
+ * @property {Array<number>=} binaryValue
+ * @property {string} name
+ * @property {string=} value
+ */
+
+/**
+ * @typedef {string} InitiatorType
+ **/
+
+/**
+ * Enum of possible initiator types.
+ *
+ * @readonly
+ * @enum {InitiatorType}
+ **/
+const InitiatorType = {
+  Other: "other",
+  Parser: "parser",
+  Preflight: "preflight",
+  Script: "script",
+};
+/**
+ * @typedef {Object} Initiator
+ * @property {InitiatorType} type
+ * @property {number=} columnNumber
+ * @property {number=} lineNumber
+ * @property {string=} request
+ * @property {StackTrace=} stackTrace
+ */
+
+/**
+ * @typedef {Object} RequestData
+ * @property {number|null} bodySize
+ *     Defaults to null.
+ * @property {Array<Cookie>} cookies
+ * @property {Array<Header>} headers
+ * @property {number} headersSize
+ * @property {string} method
+ * @property {string} request
+ * @property {FetchTimingInfo} timings
+ * @property {string} url
+ */
+
+/**
+ * @typedef {Object} BeforeRequestSentParametersProperties
+ * @property {Initiator} initiator
+ */
+
+/**
+ * Parameters for the BeforeRequestSent event
+ *
+ * @typedef {BaseParameters & BeforeRequestSentParametersProperties} BeforeRequestSentParameters
+ */
+
+/**
+ * @typedef {Object} ResponseContent
+ * @property {number|null} size
+ *     Defaults to null.
+ */
+
+/**
+ * @typedef {Object} ResponseData
+ * @property {string} url
+ * @property {string} protocol
+ * @property {number} status
+ * @property {string} statusText
+ * @property {boolean} fromCache
+ * @property {Array<Header>} headers
+ * @property {string} mimeType
+ * @property {number} bytesReceived
+ * @property {number|null} headersSize
+ *     Defaults to null.
+ * @property {number|null} bodySize
+ *     Defaults to null.
+ * @property {ResponseContent} content
+ */
+
+/**
+ * @typedef {Object} ResponseStartedParametersProperties
+ * @property {ResponseData} response
+ */
+
+/**
+ * Parameters for the ResponseStarted event
+ *
+ * @typedef {BaseParameters & ResponseStartedParametersProperties} ResponseStartedParameters
+ */
+
+/**
+ * @typedef {Object} ResponseCompletedParametersProperties
+ * @property {ResponseData} response
+ */
+
+/**
+ * Parameters for the ResponseCompleted event
+ *
+ * @typedef {BaseParameters & ResponseCompletedParametersProperties} ResponseCompletedParameters
+ */
+
+class NetworkModule extends Module {
+  #beforeRequestSentMap;
+  #networkListener;
+  #subscribedEvents;
+
+  constructor(messageHandler) {
+    super(messageHandler);
+
+    // Map of request ids to redirect counts. A WebDriver BiDi request id is
+    // identical for redirects of a given request, this map allows to know if we
+    // already emitted a beforeRequestSent event for a given request with a
+    // specific redirectCount.
+    this.#beforeRequestSentMap = new Map();
+
+    // Set of event names which have active subscriptions
+    this.#subscribedEvents = new Set();
+
+    this.#networkListener = new lazy.NetworkListener();
+    this.#networkListener.on("before-request-sent", this.#onBeforeRequestSent);
+    this.#networkListener.on("response-completed", this.#onResponseEvent);
+    this.#networkListener.on("response-started", this.#onResponseEvent);
+  }
+
+  destroy() {
+    this.#networkListener.off("before-request-sent", this.#onBeforeRequestSent);
+    this.#networkListener.off("response-completed", this.#onResponseEvent);
+    this.#networkListener.off("response-started", this.#onResponseEvent);
+
+    this.#beforeRequestSentMap = null;
+    this.#subscribedEvents = null;
+  }
+
+  #getContextInfo(browsingContext) {
+    return {
+      contextId: browsingContext.id,
+      type: lazy.WindowGlobalMessageHandler.type,
+    };
+  }
+
+  #onBeforeRequestSent = (name, data) => {
+    const { contextId, requestData, timestamp, redirectCount } = data;
+
+    const isRedirect = redirectCount > 0;
+    this.#beforeRequestSentMap.set(requestData.requestId, redirectCount);
+
+    // Bug 1805479: Handle the initiator, including stacktrace details.
+    const initiator = {
+      type: InitiatorType.Other,
+    };
+
+    const baseParameters = {
+      context: contextId,
+      isRedirect,
+      redirectCount,
+      // Bug 1805405: Handle the navigation id.
+      navigation: null,
+      request: requestData,
+      timestamp,
+    };
+
+    const beforeRequestSentEvent = {
+      ...baseParameters,
+      initiator,
+    };
+
+    const browsingContext = lazy.TabManager.getBrowsingContextById(contextId);
+    this.emitEvent(
+      "network.beforeRequestSent",
+      beforeRequestSentEvent,
+      this.#getContextInfo(browsingContext)
+    );
+  };
+
+  #onResponseEvent = (name, data) => {
+    const {
+      contextId,
+      requestData,
+      responseData,
+      timestamp,
+      redirectCount,
+    } = data;
+
+    const isRedirect = redirectCount > 0;
+
+    const requestId = requestData.requestId;
+    if (this.#beforeRequestSentMap.get(requestId) != redirectCount) {
+      throw new lazy.error.UnknownError(
+        `Redirect count of the request ${requestId} does not match the before request sent map`
+      );
+    }
+
+    const baseParameters = {
+      context: contextId,
+      isRedirect,
+      redirectCount,
+      // Bug 1805405: Handle the navigation id.
+      navigation: null,
+      request: requestData,
+      timestamp,
+    };
+
+    const responseEvent = {
+      ...baseParameters,
+      response: responseData,
+    };
+
+    const protocolEventName =
+      name === "response-started"
+        ? "network.responseStarted"
+        : "network.responseCompleted";
+
+    const browsingContext = lazy.TabManager.getBrowsingContextById(contextId);
+    this.emitEvent(
+      protocolEventName,
+      responseEvent,
+      this.#getContextInfo(browsingContext)
+    );
+  };
+
+  #startListening(event) {
+    if (this.#subscribedEvents.size == 0) {
+      this.#networkListener.startListening();
+    }
+    this.#subscribedEvents.add(event);
+  }
+
+  #stopListening(event) {
+    this.#subscribedEvents.delete(event);
+    if (this.#subscribedEvents.size == 0) {
+      this.#networkListener.stopListening();
+    }
+  }
+
+  #subscribeEvent(event) {
+    if (this.constructor.supportedEvents.includes(event)) {
+      this.#startListening(event);
+    }
+  }
+
+  #unsubscribeEvent(event) {
+    if (this.constructor.supportedEvents.includes(event)) {
+      this.#stopListening(event);
+    }
+  }
+
+  /**
+   * Internal commands
+   */
+
+  _applySessionData(params) {
+    // TODO: Bug 1775231. Move this logic to a shared module or an abstract
+    // class.
+    const { category } = params;
+    if (category === "event") {
+      const filteredSessionData = params.sessionData.filter(item =>
+        this.messageHandler.matchesContext(item.contextDescriptor)
+      );
+      for (const event of this.#subscribedEvents.values()) {
+        const hasSessionItem = filteredSessionData.some(
+          item => item.value === event
+        );
+        // If there are no session items for this context, we should unsubscribe from the event.
+        if (!hasSessionItem) {
+          this.#unsubscribeEvent(event);
+        }
+      }
+
+      // Subscribe to all events, which have an item in SessionData.
+      for (const { value } of filteredSessionData) {
+        this.#subscribeEvent(value);
+      }
+    }
+  }
+
+  static get supportedEvents() {
+    return [
+      "network.beforeRequestSent",
+      "network.responseCompleted",
+      "network.responseStarted",
+    ];
+  }
+}
+
+export const network = NetworkModule;
diff --git a/remote/webdriver-bidi/modules/root/script.sys.mjs b/remote/webdriver-bidi/modules/root/script.sys.mjs
new file mode 100644
index 0000000000..308033c816
--- /dev/null
+++ b/remote/webdriver-bidi/modules/root/script.sys.mjs
@@ -0,0 +1,532 @@
+/* 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/. */
+
+import { Module } from "chrome://remote/content/shared/messagehandler/Module.sys.mjs";
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  assert: "chrome://remote/content/shared/webdriver/Assert.sys.mjs",
+  ContextDescriptorType:
+    "chrome://remote/content/shared/messagehandler/MessageHandler.sys.mjs",
+  error: "chrome://remote/content/shared/webdriver/Errors.sys.mjs",
+  OwnershipModel: "chrome://remote/content/webdriver-bidi/RemoteValue.sys.mjs",
+  RealmType: "chrome://remote/content/webdriver-bidi/Realm.sys.mjs",
+  TabManager: "chrome://remote/content/shared/TabManager.sys.mjs",
+  WindowGlobalMessageHandler:
+    "chrome://remote/content/shared/messagehandler/WindowGlobalMessageHandler.sys.mjs",
+});
+
+/**
+ * @typedef {string} ScriptEvaluateResultType
+ **/
+
+/**
+ * Enum of possible evaluation result types.
+ *
+ * @readonly
+ * @enum {ScriptEvaluateResultType}
+ **/
+const ScriptEvaluateResultType = {
+  Exception: "exception",
+  Success: "success",
+};
+
+class ScriptModule extends Module {
+  destroy() {}
+
+  /**
+   * Used to represent a frame of a JavaScript stack trace.
+   *
+   * @typedef StackFrame
+   *
+   * @property {number} columnNumber
+   * @property {string} functionName
+   * @property {number} lineNumber
+   * @property {string} url
+   */
+
+  /**
+   * Used to represent a JavaScript stack at a point in script execution.
+   *
+   * @typedef StackTrace
+   *
+   * @property {Array<StackFrame>} callFrames
+   */
+
+  /**
+   * Used to represent a JavaScript exception.
+   *
+   * @typedef ExceptionDetails
+   *
+   * @property {number} columnNumber
+   * @property {RemoteValue} exception
+   * @property {number} lineNumber
+   * @property {StackTrace} stackTrace
+   * @property {string} text
+   */
+
+  /**
+   * Used as return value for script.evaluate, as one of the available variants
+   * {ScriptEvaluateResultException} or {ScriptEvaluateResultSuccess}.
+   *
+   * @typedef ScriptEvaluateResult
+   */
+
+  /**
+   * Used as return value for script.evaluate when the script completes with a
+   * thrown exception.
+   *
+   * @typedef ScriptEvaluateResultException
+   *
+   * @property {ExceptionDetails} exceptionDetails
+   * @property {string} realm
+   * @property {ScriptEvaluateResultType} [type=ScriptEvaluateResultType.Exception]
+   */
+
+  /**
+   * Used as return value for script.evaluate when the script completes
+   * normally.
+   *
+   * @typedef ScriptEvaluateResultSuccess
+   *
+   * @property {string} realm
+   * @property {RemoteValue} result
+   * @property {ScriptEvaluateResultType} [type=ScriptEvaluateResultType.Success]
+   */
+
+  /**
+   * Calls a provided function with given arguments and scope in the provided
+   * target, which is either a realm or a browsing context.
+   *
+   * @param {Object=} options
+   * @param {Array<RemoteValue>=} arguments
+   *     The arguments to pass to the function call.
+   * @param {boolean} awaitPromise
+   *     Determines if the command should wait for the return value of the
+   *     expression to resolve, if this return value is a Promise.
+   * @param {string} functionDeclaration
+   *     The expression to evaluate.
+   * @param {OwnershipModel=} resultOwnership
+   *     The ownership model to use for the results of this evaluation. Defaults
+   *     to `OwnershipModel.None`.
+   * @param {Object} target
+   *     The target for the evaluation, which either matches the definition for
+   *     a RealmTarget or for ContextTarget.
+   * @param {RemoteValue=} this
+   *     The value of the this keyword for the function call.
+   *
+   * @returns {ScriptEvaluateResult}
+   *
+   * @throws {InvalidArgumentError}
+   *     If any of the arguments does not have the expected type.
+   * @throws {NoSuchFrameError}
+   *     If the target cannot be found.
+   */
+  async callFunction(options = {}) {
+    const {
+      arguments: commandArguments = null,
+      awaitPromise,
+      functionDeclaration,
+      resultOwnership = lazy.OwnershipModel.None,
+      target = {},
+      this: thisParameter = null,
+    } = options;
+
+    lazy.assert.string(
+      functionDeclaration,
+      `Expected "functionDeclaration" to be a string, got ${functionDeclaration}`
+    );
+
+    lazy.assert.boolean(
+      awaitPromise,
+      `Expected "awaitPromise" to be a boolean, got ${awaitPromise}`
+    );
+
+    this.#assertResultOwnership(resultOwnership);
+
+    if (commandArguments != null) {
+      lazy.assert.array(
+        commandArguments,
+        `Expected "arguments" to be an array, got ${commandArguments}`
+      );
+    }
+
+    const { contextId, realmId, sandbox } = this.#assertTarget(target);
+    const context = await this.#getContextFromTarget({ contextId, realmId });
+    const evaluationResult = await this.messageHandler.forwardCommand({
+      moduleName: "script",
+      commandName: "callFunctionDeclaration",
+      destination: {
+        type: lazy.WindowGlobalMessageHandler.type,
+        id: context.id,
+      },
+      params: {
+        awaitPromise,
+        commandArguments,
+        functionDeclaration,
+        realmId,
+        resultOwnership,
+        sandbox,
+        thisParameter,
+      },
+    });
+
+    return this.#buildReturnValue(evaluationResult);
+  }
+
+  /**
+   * The script.disown command disowns the given handles. This does not
+   * guarantee the handled object will be garbage collected, as there can be
+   * other handles or strong ECMAScript references.
+   *
+   * @param {Object=} options
+   * @param {Array<string>} handles
+   *     Array of handle ids to disown.
+   * @param {Object} target
+   *     The target owning the handles, which either matches the definition for
+   *     a RealmTarget or for ContextTarget.
+   */
+  async disown(options = {}) {
+    const { handles, target = {} } = options;
+
+    lazy.assert.array(
+      handles,
+      `Expected "handles" to be an array, got ${handles}`
+    );
+    handles.forEach(handle => {
+      lazy.assert.string(
+        handle,
+        `Expected "handles" to be an array of strings, got ${handle}`
+      );
+    });
+
+    const { contextId, realmId, sandbox } = this.#assertTarget(target);
+    const context = await this.#getContextFromTarget({ contextId, realmId });
+    await this.messageHandler.forwardCommand({
+      moduleName: "script",
+      commandName: "disownHandles",
+      destination: {
+        type: lazy.WindowGlobalMessageHandler.type,
+        id: context.id,
+      },
+      params: {
+        handles,
+        realmId,
+        sandbox,
+      },
+    });
+  }
+
+  /**
+   * Evaluate a provided expression in the provided target, which is either a
+   * realm or a browsing context.
+   *
+   * @param {Object=} options
+   * @param {boolean} awaitPromise
+   *     Determines if the command should wait for the return value of the
+   *     expression to resolve, if this return value is a Promise.
+   * @param {string} expression
+   *     The expression to evaluate.
+   * @param {OwnershipModel=} resultOwnership
+   *     The ownership model to use for the results of this evaluation. Defaults
+   *     to `OwnershipModel.None`.
+   * @param {Object} target
+   *     The target for the evaluation, which either matches the definition for
+   *     a RealmTarget or for ContextTarget.
+   *
+   * @returns {ScriptEvaluateResult}
+   *
+   * @throws {InvalidArgumentError}
+   *     If any of the arguments does not have the expected type.
+   * @throws {NoSuchFrameError}
+   *     If the target cannot be found.
+   */
+  async evaluate(options = {}) {
+    const {
+      awaitPromise,
+      expression: source,
+      resultOwnership = lazy.OwnershipModel.None,
+      target = {},
+    } = options;
+
+    lazy.assert.string(
+      source,
+      `Expected "expression" to be a string, got ${source}`
+    );
+
+    lazy.assert.boolean(
+      awaitPromise,
+      `Expected "awaitPromise" to be a boolean, got ${awaitPromise}`
+    );
+
+    this.#assertResultOwnership(resultOwnership);
+
+    const { contextId, realmId, sandbox } = this.#assertTarget(target);
+    const context = await this.#getContextFromTarget({ contextId, realmId });
+    const evaluationResult = await this.messageHandler.forwardCommand({
+      moduleName: "script",
+      commandName: "evaluateExpression",
+      destination: {
+        type: lazy.WindowGlobalMessageHandler.type,
+        id: context.id,
+      },
+      params: {
+        awaitPromise,
+        expression: source,
+        realmId,
+        resultOwnership,
+        sandbox,
+      },
+    });
+
+    return this.#buildReturnValue(evaluationResult);
+  }
+
+  /**
+   * An object that holds basic information about a realm.
+   *
+   * @typedef BaseRealmInfo
+   *
+   * @property {string} id
+   *     The realm unique identifier.
+   * @property {string} origin
+   *     The serialization of an origin.
+   */
+
+  /**
+   *
+   * @typedef WindowRealmInfoProperties
+   *
+   * @property {string} context
+   *     The browsing context id, associated with the realm.
+   * @property {string=} sandbox
+   *     The name of the sandbox. If the value is null or empty
+   *     string, the default realm will be returned.
+   * @property {RealmType.Window} type
+   *     The window realm type.
+   */
+
+  /**
+   * An object that holds information about a window realm.
+   *
+   * @typedef {BaseRealmInfo & WindowRealmInfoProperties} WindowRealmInfo
+   */
+
+  /**
+   * An object that holds information about a realm.
+   *
+   * @typedef {WindowRealmInfo} RealmInfo
+   */
+
+  /**
+   * An object that holds a list of realms.
+   *
+   * @typedef ScriptGetRealmsResult
+   *
+   * @property {Array<RealmInfo>} realms
+   *     List of realms.
+   */
+
+  /**
+   * Returns a list of all realms, optionally filtered to realms
+   * of a specific type, or to the realms associated with
+   * a specified browsing context.
+   *
+   * @param {Object=} options
+   * @param {string=} context
+   *     The id of the browsing context to filter
+   *     only realms associated with it. If not provided, return realms
+   *     associated with all browsing contexts.
+   * @param {RealmType=} type
+   *     Type of realm to filter.
+   *     If not provided, return realms of all types.
+   *
+   * @returns {ScriptGetRealmsResult}
+   *
+   * @throws {InvalidArgumentError}
+   *     If any of the arguments does not have the expected type.
+   * @throws {NoSuchFrameError}
+   *     If the context cannot be found.
+   */
+  async getRealms(options = {}) {
+    const { context: contextId = null, type = null } = options;
+    const destination = {};
+
+    if (contextId !== null) {
+      lazy.assert.string(
+        contextId,
+        `Expected "context" to be a string, got ${contextId}`
+      );
+      destination.id = this.#getBrowsingContext(contextId).id;
+    } else {
+      destination.contextDescriptor = {
+        type: lazy.ContextDescriptorType.All,
+      };
+    }
+
+    if (type !== null) {
+      const supportedRealmTypes = Object.values(lazy.RealmType);
+      if (!supportedRealmTypes.includes(type)) {
+        throw new lazy.error.InvalidArgumentError(
+          `Expected "type" to be one of ${supportedRealmTypes}, got ${type}`
+        );
+      }
+
+      // Remove this check when other realm types are supported
+      if (type !== lazy.RealmType.Window) {
+        throw new lazy.error.UnsupportedOperationError(
+          `Unsupported "type": ${type}. Only "type" ${lazy.RealmType.Window} is currently supported.`
+        );
+      }
+    }
+
+    return { realms: await this.#getRealmInfos(destination) };
+  }
+
+  #assertResultOwnership(resultOwnership) {
+    if (
+      ![lazy.OwnershipModel.None, lazy.OwnershipModel.Root].includes(
+        resultOwnership
+      )
+    ) {
+      throw new lazy.error.InvalidArgumentError(
+        `Expected "resultOwnership" to be one of ${Object.values(
+          lazy.OwnershipModel
+        )}, got ${resultOwnership}`
+      );
+    }
+  }
+
+  #assertTarget(target) {
+    lazy.assert.object(
+      target,
+      `Expected "target" to be an object, got ${target}`
+    );
+
+    const {
+      context: contextId = null,
+      realm: realmId = null,
+      sandbox = null,
+    } = target;
+
+    if (realmId != null && (contextId != null || sandbox != null)) {
+      throw new lazy.error.InvalidArgumentError(
+        `A context and a realm reference are mutually exclusive`
+      );
+    }
+
+    if (contextId != null) {
+      lazy.assert.string(
+        contextId,
+        `Expected "context" to be a string, got ${contextId}`
+      );
+
+      if (sandbox != null) {
+        lazy.assert.string(
+          sandbox,
+          `Expected "sandbox" to be a string, got ${sandbox}`
+        );
+      }
+    } else if (realmId != null) {
+      lazy.assert.string(
+        realmId,
+        `Expected "realm" to be a string, got ${realmId}`
+      );
+    } else {
+      throw new lazy.error.InvalidArgumentError(`No context or realm provided`);
+    }
+
+    return { contextId, realmId, sandbox };
+  }
+
+  #buildReturnValue(evaluationResult) {
+    const rv = { realm: evaluationResult.realmId };
+    switch (evaluationResult.evaluationStatus) {
+      // TODO: Compare with EvaluationStatus.Normal after Bug 1774444 is fixed.
+      case "normal":
+        rv.type = ScriptEvaluateResultType.Success;
+        rv.result = evaluationResult.result;
+        break;
+      // TODO: Compare with EvaluationStatus.Throw after Bug 1774444 is fixed.
+      case "throw":
+        rv.type = ScriptEvaluateResultType.Exception;
+        rv.exceptionDetails = evaluationResult.exceptionDetails;
+        break;
+      default:
+        throw new lazy.error.UnsupportedOperationError(
+          `Unsupported evaluation status ${evaluationResult.evaluationStatus}`
+        );
+    }
+    return rv;
+  }
+
+  #getBrowsingContext(contextId) {
+    const context = lazy.TabManager.getBrowsingContextById(contextId);
+    if (context === null) {
+      throw new lazy.error.NoSuchFrameError(
+        `Browsing Context with id ${contextId} not found`
+      );
+    }
+
+    if (!context.currentWindowGlobal) {
+      throw new lazy.error.NoSuchFrameError(
+        `No window found for BrowsingContext with id ${contextId}`
+      );
+    }
+
+    return context;
+  }
+
+  async #getContextFromTarget({ contextId, realmId }) {
+    if (contextId !== null) {
+      return this.#getBrowsingContext(contextId);
+    }
+
+    const destination = {
+      contextDescriptor: {
+        type: lazy.ContextDescriptorType.All,
+      },
+    };
+    const realms = await this.#getRealmInfos(destination);
+    const realm = realms.find(realm => realm.realm == realmId);
+
+    if (realm && realm.context !== null) {
+      return this.#getBrowsingContext(realm.context);
+    }
+
+    throw new lazy.error.NoSuchFrameError(`Realm with id ${realmId} not found`);
+  }
+
+  async #getRealmInfos(destination) {
+    let realms = await this.messageHandler.forwardCommand({
+      moduleName: "script",
+      commandName: "getWindowRealms",
+      destination: {
+        type: lazy.WindowGlobalMessageHandler.type,
+        ...destination,
+      },
+    });
+
+    const isBroadcast = !!destination.contextDescriptor;
+    if (!isBroadcast) {
+      realms = [realms];
+    }
+
+    return realms
+      .flat()
+      .map(realm => {
+        // Resolve browsing context to a TabManager id.
+        realm.context = lazy.TabManager.getIdForBrowsingContext(realm.context);
+        return realm;
+      })
+      .filter(realm => realm.context !== null);
+  }
+
+  static get supportedEvents() {
+    return [];
+  }
+}
+
+export const script = ScriptModule;
diff --git a/remote/webdriver-bidi/modules/root/session.sys.mjs b/remote/webdriver-bidi/modules/root/session.sys.mjs
new file mode 100644
index 0000000000..281b913f32
--- /dev/null
+++ b/remote/webdriver-bidi/modules/root/session.sys.mjs
@@ -0,0 +1,406 @@
+/* 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/. */
+
+import { Module } from "chrome://remote/content/shared/messagehandler/Module.sys.mjs";
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  assert: "chrome://remote/content/shared/webdriver/Assert.sys.mjs",
+  ContextDescriptorType:
+    "chrome://remote/content/shared/messagehandler/MessageHandler.sys.mjs",
+  error: "chrome://remote/content/shared/webdriver/Errors.sys.mjs",
+  RootMessageHandler:
+    "chrome://remote/content/shared/messagehandler/RootMessageHandler.sys.mjs",
+  TabManager: "chrome://remote/content/shared/TabManager.sys.mjs",
+});
+
+class SessionModule extends Module {
+  #browsingContextIdEventMap;
+  #globalEventSet;
+
+  constructor(messageHandler) {
+    super(messageHandler);
+
+    // Map with top-level browsing context id keys and values
+    // that are a set of event names for events
+    // that are enabled in the given browsing context.
+    // TODO: Bug 1804417. Use navigable instead of browsing context id.
+    this.#browsingContextIdEventMap = new Map();
+
+    // Set of event names which are strings of the form [moduleName].[eventName]
+    // for events that are enabled for all browsing contexts.
+    // We should only add an actual event listener on the MessageHandler the
+    // first time an event is subscribed to.
+    this.#globalEventSet = new Set();
+  }
+
+  destroy() {
+    this.#browsingContextIdEventMap = null;
+    this.#globalEventSet = null;
+  }
+
+  /**
+   * Commands
+   */
+
+  /**
+   * Enable certain events either globally, or for a list of browsing contexts.
+   *
+   * @params {Object=} params
+   * @params {Array<string>} events
+   *     List of events to subscribe to.
+   * @params {Array<string>=} contexts
+   *     Optional list of top-level browsing context ids
+   *     to subscribe the events for.
+   *
+   * @throws {InvalidArgumentError}
+   *     If <var>events</var> or <var>contexts</var> are not valid types.
+   */
+  async subscribe(params = {}) {
+    const { events, contexts: contextIds = null } = params;
+
+    // Check input types until we run schema validation.
+    lazy.assert.array(events, "events: array value expected");
+    events.forEach(name => {
+      lazy.assert.string(name, `${name}: string value expected`);
+    });
+
+    if (contextIds !== null) {
+      lazy.assert.array(contextIds, "contexts: array value expected");
+      contextIds.forEach(contextId => {
+        lazy.assert.string(contextId, `${contextId}: string value expected`);
+      });
+    }
+
+    const listeners = this.#updateEventMap(events, contextIds, true);
+
+    // TODO: Bug 1801284. Add subscribe priority sorting of subscribeStepEvents (step 4 to 6, and 8).
+
+    // Subscribe to the relevant engine-internal events.
+    await this.messageHandler.eventsDispatcher.update(listeners);
+  }
+
+  /**
+   * Disable certain events either globally, or for a list of browsing contexts.
+   *
+   * @params {Object=} params
+   * @params {Array<string>} events
+   *     List of events to unsubscribe from.
+   * @params {Array<string>=} contexts
+   *     Optional list of top-level browsing context ids
+   *     to unsubscribe the events from.
+   *
+   * @throws {InvalidArgumentError}
+   *     If <var>events</var> or <var>contexts</var> are not valid types.
+   */
+  async unsubscribe(params = {}) {
+    const { events, contexts: contextIds = null } = params;
+
+    // Check input types until we run schema validation.
+    lazy.assert.array(events, "events: array value expected");
+    events.forEach(name => {
+      lazy.assert.string(name, `${name}: string value expected`);
+    });
+    if (contextIds !== null) {
+      lazy.assert.array(contextIds, "contexts: array value expected");
+      contextIds.forEach(contextId => {
+        lazy.assert.string(contextId, `${contextId}: string value expected`);
+      });
+    }
+
+    const listeners = this.#updateEventMap(events, contextIds, false);
+
+    // Unsubscribe from the relevant engine-internal events.
+    await this.messageHandler.eventsDispatcher.update(listeners);
+  }
+
+  #assertModuleSupportsEvent(moduleName, event) {
+    const rootModuleClass = this.#getRootModuleClass(moduleName);
+    if (!rootModuleClass?.supportsEvent(event)) {
+      throw new lazy.error.InvalidArgumentError(
+        `${event} is not a valid event name`
+      );
+    }
+  }
+
+  #getBrowserIdForContextId(contextId) {
+    const context = lazy.TabManager.getBrowsingContextById(contextId);
+    if (!context) {
+      throw new lazy.error.NoSuchFrameError(
+        `Browsing context with id ${contextId} not found`
+      );
+    }
+
+    return context.browserId;
+  }
+
+  #getRootModuleClass(moduleName) {
+    // Modules which support event subscriptions should have a root module
+    // defining supported events.
+    const rootDestination = { type: lazy.RootMessageHandler.type };
+    const moduleClasses = this.messageHandler.getAllModuleClasses(
+      moduleName,
+      rootDestination
+    );
+
+    if (!moduleClasses.length) {
+      throw new lazy.error.InvalidArgumentError(
+        `Module ${moduleName} does not exist`
+      );
+    }
+
+    return moduleClasses[0];
+  }
+
+  #getTopBrowsingContextId(contextId) {
+    const context = lazy.TabManager.getBrowsingContextById(contextId);
+    if (!context) {
+      throw new lazy.error.NoSuchFrameError(
+        `Browsing context with id ${contextId} not found`
+      );
+    }
+    const topContext = context.top;
+    return lazy.TabManager.getIdForBrowsingContext(topContext);
+  }
+
+  /**
+   * Obtain a set of events based on the given event name.
+   *
+   * Could contain a period for a specific event,
+   * or just the module name for all events.
+   *
+   * @param {string} event
+   *     Name of the event to process.
+   *
+   * @returns {Set<string>}
+   *     A Set with the expanded events in the form of `<module>.<event>`.
+   *
+   * @throws {InvalidArgumentError}
+   *     If <var>event</var> does not reference a valid event.
+   */
+  #obtainEvents(event) {
+    const events = new Set();
+
+    // Check if a period is present that splits the event name into the module,
+    // and the actual event. Hereby only care about the first found instance.
+    const index = event.indexOf(".");
+    if (index >= 0) {
+      const [moduleName] = event.split(".");
+      this.#assertModuleSupportsEvent(moduleName, event);
+      events.add(event);
+    } else {
+      // Interpret the name as module, and register all its available events
+      const rootModuleClass = this.#getRootModuleClass(event);
+      const supportedEvents = rootModuleClass?.supportedEvents;
+
+      for (const eventName of supportedEvents) {
+        events.add(eventName);
+      }
+    }
+
+    return events;
+  }
+
+  /**
+   * Obtain a list of event enabled browsing context ids.
+   *
+   * @see https://w3c.github.io/webdriver-bidi/#event-enabled-browsing-contexts
+   *
+   * @param {string} eventName
+   *     The name of the event.
+   *
+   * @return {Set<string>} The set of browsing context.
+   */
+  #obtainEventEnabledBrowsingContextIds(eventName) {
+    const contextIds = new Set();
+    for (const [
+      contextId,
+      events,
+    ] of this.#browsingContextIdEventMap.entries()) {
+      if (events.has(eventName)) {
+        // Check that a browsing context still exists for a given id
+        const context = lazy.TabManager.getBrowsingContextById(contextId);
+        if (context) {
+          contextIds.add(contextId);
+        }
+      }
+    }
+
+    return contextIds;
+  }
+
+  #onMessageHandlerEvent = (name, event) => {
+    this.messageHandler.emitProtocolEvent(name, event);
+  };
+
+  /**
+   * Update global event state for top-level browsing contexts.
+   *
+   * @see https://w3c.github.io/webdriver-bidi/#update-the-event-map
+   *
+   * @param {Array<string>} requestedEventNames
+   *     The list of the event names to run the update for.
+   * @param {Array<string>|null} browsingContextIds
+   *     The list of the browsing context ids to update or null.
+   * @param {boolean} enabled
+   *     True, if events have to be enabled. Otherwise false.
+   *
+   * @return {Array<Subscription>} subscriptions
+   *     The list of information to subscribe/unsubscribe to.
+   *
+   * @throws {InvalidArgumentError}
+   *     If failed unsubscribe from event from <var>requestedEventNames</var> for
+   *     browsing context id from <var>browsingContextIds</var>, if present.
+   */
+  #updateEventMap(requestedEventNames, browsingContextIds, enabled) {
+    const globalEventSet = new Set(this.#globalEventSet);
+    const eventMap = structuredClone(this.#browsingContextIdEventMap);
+
+    const eventNames = new Set();
+
+    requestedEventNames.forEach(name => {
+      this.#obtainEvents(name).forEach(event => eventNames.add(event));
+    });
+    const enabledEvents = new Map();
+    const subscriptions = [];
+
+    if (browsingContextIds === null) {
+      // Subscribe or unsubscribe events for all browsing contexts.
+      if (enabled) {
+        // Subscribe to each event.
+
+        // Get the list of all top level browsing context ids.
+        const allTopBrowsingContextIds = lazy.TabManager.allBrowserUniqueIds;
+
+        for (const eventName of eventNames) {
+          if (!globalEventSet.has(eventName)) {
+            const alreadyEnabledContextIds = this.#obtainEventEnabledBrowsingContextIds(
+              eventName
+            );
+            globalEventSet.add(eventName);
+            for (const contextId of alreadyEnabledContextIds) {
+              eventMap.get(contextId).delete(eventName);
+
+              // Since we're going to subscribe to all top-level
+              // browsing context ids to not have duplicate subscriptions,
+              // we have to unsubscribe from already subscribed.
+              subscriptions.push({
+                event: eventName,
+                contextDescriptor: {
+                  type: lazy.ContextDescriptorType.TopBrowsingContext,
+                  id: this.#getBrowserIdForContextId(contextId),
+                },
+                callback: this.#onMessageHandlerEvent,
+                enable: false,
+              });
+            }
+
+            // Get a list of all top-level browsing context ids
+            // that are not contained in alreadyEnabledContextIds.
+            const newlyEnabledContextIds = allTopBrowsingContextIds.filter(
+              contextId => !alreadyEnabledContextIds.has(contextId)
+            );
+
+            enabledEvents.set(eventName, newlyEnabledContextIds);
+
+            subscriptions.push({
+              event: eventName,
+              contextDescriptor: {
+                type: lazy.ContextDescriptorType.All,
+              },
+              callback: this.#onMessageHandlerEvent,
+              enable: true,
+            });
+          }
+        }
+      } else {
+        // Unsubscribe each event which has a global subscription.
+        for (const eventName of eventNames) {
+          if (globalEventSet.has(eventName)) {
+            globalEventSet.delete(eventName);
+
+            subscriptions.push({
+              event: eventName,
+              contextDescriptor: {
+                type: lazy.ContextDescriptorType.All,
+              },
+              callback: this.#onMessageHandlerEvent,
+              enable: false,
+            });
+          } else {
+            throw new lazy.error.InvalidArgumentError(
+              `Failed to unsubscribe from event ${eventName}`
+            );
+          }
+        }
+      }
+    } else {
+      // Subscribe or unsubscribe events for given list of browsing context ids.
+      const targets = new Map();
+      for (const contextId of browsingContextIds) {
+        const topLevelContextId = this.#getTopBrowsingContextId(contextId);
+        if (!eventMap.has(topLevelContextId)) {
+          eventMap.set(topLevelContextId, new Set());
+        }
+        targets.set(topLevelContextId, eventMap.get(topLevelContextId));
+      }
+
+      for (const eventName of eventNames) {
+        // Do nothing if we want to subscribe,
+        // but the event has already a global subscription.
+        if (enabled && this.#globalEventSet.has(eventName)) {
+          continue;
+        }
+        for (const [contextId, target] of targets.entries()) {
+          // Subscribe if an event doesn't have a subscription for a specific context id.
+          if (enabled && !target.has(eventName)) {
+            target.add(eventName);
+            if (!enabledEvents.has(eventName)) {
+              enabledEvents.set(eventName, new Set());
+            }
+            enabledEvents.get(eventName).add(contextId);
+
+            subscriptions.push({
+              event: eventName,
+              contextDescriptor: {
+                type: lazy.ContextDescriptorType.TopBrowsingContext,
+                id: this.#getBrowserIdForContextId(contextId),
+              },
+              callback: this.#onMessageHandlerEvent,
+              enable: true,
+            });
+          } else if (!enabled) {
+            // Unsubscribe from each event for a specific context id if the event has a subscription.
+            if (target.has(eventName)) {
+              target.delete(eventName);
+
+              subscriptions.push({
+                event: eventName,
+                contextDescriptor: {
+                  type: lazy.ContextDescriptorType.TopBrowsingContext,
+                  id: this.#getBrowserIdForContextId(contextId),
+                },
+                callback: this.#onMessageHandlerEvent,
+                enable: false,
+              });
+            } else {
+              throw new lazy.error.InvalidArgumentError(
+                `Failed to unsubscribe from event ${eventName} for context ${contextId}`
+              );
+            }
+          }
+        }
+      }
+    }
+
+    this.#globalEventSet = globalEventSet;
+    this.#browsingContextIdEventMap = eventMap;
+
+    return subscriptions;
+  }
+}
+
+// To export the class as lower-case
+export const session = SessionModule;
diff --git a/remote/webdriver-bidi/modules/windowglobal-in-root/browsingContext.sys.mjs b/remote/webdriver-bidi/modules/windowglobal-in-root/browsingContext.sys.mjs
new file mode 100644
index 0000000000..68a220cee2
--- /dev/null
+++ b/remote/webdriver-bidi/modules/windowglobal-in-root/browsingContext.sys.mjs
@@ -0,0 +1,31 @@
+/* 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/. */
+
+import { Module } from "chrome://remote/content/shared/messagehandler/Module.sys.mjs";
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  TabManager: "chrome://remote/content/shared/TabManager.sys.mjs",
+});
+
+class BrowsingContextModule extends Module {
+  destroy() {}
+
+  interceptEvent(name, payload) {
+    if (
+      name == "browsingContext.domContentLoaded" ||
+      name == "browsingContext.load"
+    ) {
+      // Resolve browsing context to a TabManager id.
+      payload.context = lazy.TabManager.getIdForBrowsingContext(
+        payload.context
+      );
+    }
+
+    return payload;
+  }
+}
+
+export const browsingContext = BrowsingContextModule;
diff --git a/remote/webdriver-bidi/modules/windowglobal-in-root/log.sys.mjs b/remote/webdriver-bidi/modules/windowglobal-in-root/log.sys.mjs
new file mode 100644
index 0000000000..e6f62a29ad
--- /dev/null
+++ b/remote/webdriver-bidi/modules/windowglobal-in-root/log.sys.mjs
@@ -0,0 +1,28 @@
+/* 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/. */
+
+import { Module } from "chrome://remote/content/shared/messagehandler/Module.sys.mjs";
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  TabManager: "chrome://remote/content/shared/TabManager.sys.mjs",
+});
+
+class LogModule extends Module {
+  destroy() {}
+
+  interceptEvent(name, payload) {
+    if (name == "log.entryAdded") {
+      // Resolve browsing context to a TabManager id.
+      payload.source.context = lazy.TabManager.getIdForBrowsingContext(
+        payload.source.context
+      );
+    }
+
+    return payload;
+  }
+}
+
+export const log = LogModule;
diff --git a/remote/webdriver-bidi/modules/windowglobal/browsingContext.sys.mjs b/remote/webdriver-bidi/modules/windowglobal/browsingContext.sys.mjs
new file mode 100644
index 0000000000..65dd71cefb
--- /dev/null
+++ b/remote/webdriver-bidi/modules/windowglobal/browsingContext.sys.mjs
@@ -0,0 +1,159 @@
+/* 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/. */
+
+import { Module } from "chrome://remote/content/shared/messagehandler/Module.sys.mjs";
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  LoadListener: "chrome://remote/content/shared/listeners/LoadListener.sys.mjs",
+});
+
+class BrowsingContextModule extends Module {
+  #loadListener;
+  #subscribedEvents;
+
+  constructor(messageHandler) {
+    super(messageHandler);
+
+    // Setup the LoadListener as early as possible.
+    this.#loadListener = new lazy.LoadListener(this.messageHandler.window);
+    this.#loadListener.on("DOMContentLoaded", this.#onDOMContentLoaded);
+    this.#loadListener.on("load", this.#onLoad);
+
+    // Set of event names which have active subscriptions.
+    this.#subscribedEvents = new Set();
+  }
+
+  destroy() {
+    this.#loadListener.destroy();
+    this.#subscribedEvents = null;
+  }
+
+  #getNavigationInfo(data) {
+    return {
+      context: this.messageHandler.context,
+      // TODO: The navigation id should be a real id mapped to the navigation.
+      // See https://bugzilla.mozilla.org/show_bug.cgi?id=1763122
+      navigation: null,
+      timestamp: Date.now(),
+      url: data.target.baseURI,
+    };
+  }
+
+  #startListening() {
+    if (this.#subscribedEvents.size == 0) {
+      this.#loadListener.startListening();
+    }
+  }
+
+  #stopListening() {
+    if (this.#subscribedEvents.size == 0) {
+      this.#loadListener.stopListening();
+    }
+  }
+
+  #subscribeEvent(event) {
+    switch (event) {
+      case "browsingContext._documentInteractive":
+        this.#startListening();
+        this.#subscribedEvents.add("browsingContext._documentInteractive");
+        break;
+      case "browsingContext.domContentLoaded":
+        this.#startListening();
+        this.#subscribedEvents.add("browsingContext.domContentLoaded");
+        break;
+      case "browsingContext.load":
+        this.#startListening();
+        this.#subscribedEvents.add("browsingContext.load");
+        break;
+    }
+  }
+
+  #unsubscribeEvent(event) {
+    switch (event) {
+      case "browsingContext._documentInteractive":
+        this.#subscribedEvents.delete("browsingContext._documentInteractive");
+        break;
+      case "browsingContext.domContentLoaded":
+        this.#subscribedEvents.delete("browsingContext.domContentLoaded");
+        break;
+      case "browsingContext.load":
+        this.#subscribedEvents.delete("browsingContext.load");
+        break;
+    }
+
+    this.#stopListening();
+  }
+
+  #onDOMContentLoaded = (eventName, data) => {
+    if (this.#subscribedEvents.has("browsingContext._documentInteractive")) {
+      this.messageHandler.emitEvent("browsingContext._documentInteractive", {
+        baseURL: data.target.baseURI,
+        contextId: this.messageHandler.contextId,
+        documentURL: data.target.URL,
+        innerWindowId: this.messageHandler.innerWindowId,
+        readyState: data.target.readyState,
+      });
+    }
+
+    if (this.#subscribedEvents.has("browsingContext.domContentLoaded")) {
+      this.emitEvent(
+        "browsingContext.domContentLoaded",
+        this.#getNavigationInfo(data)
+      );
+    }
+  };
+
+  #onLoad = (eventName, data) => {
+    if (this.#subscribedEvents.has("browsingContext.load")) {
+      this.emitEvent("browsingContext.load", this.#getNavigationInfo(data));
+    }
+  };
+
+  /**
+   * Internal commands
+   */
+
+  _applySessionData(params) {
+    // TODO: Bug 1775231. Move this logic to a shared module or an abstract
+    // class.
+    const { category } = params;
+    if (category === "event") {
+      const filteredSessionData = params.sessionData.filter(item =>
+        this.messageHandler.matchesContext(item.contextDescriptor)
+      );
+      for (const event of this.#subscribedEvents.values()) {
+        const hasSessionItem = filteredSessionData.some(
+          item => item.value === event
+        );
+        // If there are no session items for this context, we should unsubscribe from the event.
+        if (!hasSessionItem) {
+          this.#unsubscribeEvent(event);
+        }
+      }
+
+      // Subscribe to all events, which have an item in SessionData.
+      for (const { value } of filteredSessionData) {
+        this.#subscribeEvent(value);
+      }
+    }
+  }
+
+  _getBaseURL() {
+    return this.messageHandler.window.document.baseURI;
+  }
+
+  _getScreenshotRect() {
+    const win = this.messageHandler.window;
+    return new DOMRect(
+      win.pageXOffset,
+      win.pageYOffset,
+      win.innerWidth,
+      win.innerHeight
+    );
+  }
+}
+
+export const browsingContext = BrowsingContextModule;
diff --git a/remote/webdriver-bidi/modules/windowglobal/log.sys.mjs b/remote/webdriver-bidi/modules/windowglobal/log.sys.mjs
new file mode 100644
index 0000000000..46e2340936
--- /dev/null
+++ b/remote/webdriver-bidi/modules/windowglobal/log.sys.mjs
@@ -0,0 +1,242 @@
+/* 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/. */
+
+import { Module } from "chrome://remote/content/shared/messagehandler/Module.sys.mjs";
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  ConsoleAPIListener:
+    "chrome://remote/content/shared/listeners/ConsoleAPIListener.sys.mjs",
+  ConsoleListener:
+    "chrome://remote/content/shared/listeners/ConsoleListener.sys.mjs",
+  isChromeFrame: "chrome://remote/content/shared/Stack.sys.mjs",
+  OwnershipModel: "chrome://remote/content/webdriver-bidi/RemoteValue.sys.mjs",
+  serialize: "chrome://remote/content/webdriver-bidi/RemoteValue.sys.mjs",
+});
+
+class LogModule extends Module {
+  #consoleAPIListener;
+  #consoleMessageListener;
+  #subscribedEvents;
+
+  constructor(messageHandler) {
+    super(messageHandler);
+
+    // Create the console-api listener and listen on "message" events.
+    this.#consoleAPIListener = new lazy.ConsoleAPIListener(
+      this.messageHandler.innerWindowId
+    );
+    this.#consoleAPIListener.on("message", this.#onConsoleAPIMessage);
+
+    // Create the console listener and listen on error messages.
+    this.#consoleMessageListener = new lazy.ConsoleListener(
+      this.messageHandler.innerWindowId
+    );
+    this.#consoleMessageListener.on("error", this.#onJavaScriptError);
+
+    // Set of event names which have active subscriptions.
+    this.#subscribedEvents = new Set();
+  }
+
+  destroy() {
+    this.#consoleAPIListener.off("message", this.#onConsoleAPIMessage);
+    this.#consoleAPIListener.destroy();
+    this.#consoleMessageListener.off("error", this.#onJavaScriptError);
+    this.#consoleMessageListener.destroy();
+
+    this.#subscribedEvents = null;
+  }
+
+  #buildSource() {
+    return {
+      realm: this.messageHandler.window.windowGlobalChild?.innerWindowId.toString(),
+      context: this.messageHandler.context,
+    };
+  }
+
+  /**
+   * Map the internal stacktrace representation to a WebDriver BiDi
+   * compatible one.
+   *
+   * Currently chrome frames will be filtered out until chrome scope
+   * is supported (bug 1722679).
+   *
+   * @param {Array<StackFrame>=} stackTrace
+   *     Stack frames to process.
+   *
+   * @returns {Object=} Object, containing the list of frames as `callFrames`.
+   */
+  #buildStackTrace(stackTrace) {
+    if (stackTrace == undefined) {
+      return undefined;
+    }
+
+    const callFrames = stackTrace
+      .filter(frame => !lazy.isChromeFrame(frame))
+      .map(frame => {
+        return {
+          columnNumber: frame.columnNumber - 1,
+          functionName: frame.functionName,
+          lineNumber: frame.lineNumber - 1,
+          url: frame.filename,
+        };
+      });
+
+    return { callFrames };
+  }
+
+  #getLogEntryLevelFromConsoleMethod(method) {
+    switch (method) {
+      case "assert":
+      case "error":
+        return "error";
+      case "debug":
+      case "trace":
+        return "debug";
+      case "warn":
+        return "warn";
+      default:
+        return "info";
+    }
+  }
+
+  #onConsoleAPIMessage = (eventName, data = {}) => {
+    const {
+      // `arguments` cannot be used as variable name in functions
+      arguments: messageArguments,
+      // `level` corresponds to the console method used
+      level: method,
+      stacktrace,
+      timeStamp,
+    } = data;
+
+    // Step numbers below refer to the specifications at
+    //   https://w3c.github.io/webdriver-bidi/#event-log-entryAdded
+
+    // Translate the console message method to a log.LogEntry level
+    const logEntrylevel = this.#getLogEntryLevelFromConsoleMethod(method);
+
+    // Use the message's timeStamp or fallback on the current time value.
+    const timestamp = timeStamp || Date.now();
+
+    // Start assembling the text representation of the message.
+    let text = "";
+
+    // Formatters have already been applied at this points.
+    // message.arguments corresponds to the "formatted args" from the
+    // specifications.
+
+    // Concatenate all formatted arguments in text
+    // TODO: For m1 we only support string arguments, so we rely on the builtin
+    // toString for each argument which will be available in message.arguments.
+    const args = messageArguments || [];
+    text += args.map(String).join(" ");
+
+    // Serialize each arg as remote value.
+    const serializedArgs = [];
+    for (const arg of args) {
+      // Note that we can pass a `null` realm for now since realms are only
+      // involved when creating object references, which will not happen with
+      // OwnershipModel.None. This will be revisited in Bug 1731589.
+      serializedArgs.push(
+        lazy.serialize(arg, 1, lazy.OwnershipModel.None, new Map(), null)
+      );
+    }
+
+    // Set source to an object which contains realm and browsing context.
+    const source = this.#buildSource();
+
+    // Set stack trace only for certain methods.
+    let stackTrace;
+    if (["assert", "error", "trace", "warn"].includes(method)) {
+      stackTrace = this.#buildStackTrace(stacktrace);
+    }
+
+    // Build the ConsoleLogEntry
+    const entry = {
+      type: "console",
+      method,
+      source,
+      args: serializedArgs,
+      level: logEntrylevel,
+      text,
+      timestamp,
+      stackTrace,
+    };
+
+    // TODO: Those steps relate to:
+    // - emitting associated BrowsingContext. See log.entryAdded full support
+    //   in https://bugzilla.mozilla.org/show_bug.cgi?id=1724669#c0
+    // - handling cases where session doesn't exist or the event is not
+    //   monitored. The implementation differs from the spec here because we
+    //   only react to events if there is a session & if the session subscribed
+    //   to those events.
+
+    this.emitEvent("log.entryAdded", entry);
+  };
+
+  #onJavaScriptError = (eventName, data = {}) => {
+    const { level, message, stacktrace, timeStamp } = data;
+
+    // Build the JavascriptLogEntry
+    const entry = {
+      type: "javascript",
+      level,
+      source: this.#buildSource(),
+      text: message,
+      timestamp: timeStamp || Date.now(),
+      stackTrace: this.#buildStackTrace(stacktrace),
+    };
+
+    this.emitEvent("log.entryAdded", entry);
+  };
+
+  #subscribeEvent(event) {
+    if (event === "log.entryAdded") {
+      this.#consoleAPIListener.startListening();
+      this.#consoleMessageListener.startListening();
+      this.#subscribedEvents.add(event);
+    }
+  }
+
+  #unsubscribeEvent(event) {
+    if (event === "log.entryAdded") {
+      this.#consoleAPIListener.stopListening();
+      this.#consoleMessageListener.stopListening();
+      this.#subscribedEvents.delete(event);
+    }
+  }
+
+  /**
+   * Internal commands
+   */
+
+  _applySessionData(params) {
+    // TODO: Bug 1775231. Move this logic to a shared module or an abstract
+    // class.
+    const { category } = params;
+    if (category === "event") {
+      const filteredSessionData = params.sessionData.filter(item =>
+        this.messageHandler.matchesContext(item.contextDescriptor)
+      );
+      for (const event of this.#subscribedEvents.values()) {
+        const hasSessionItem = filteredSessionData.some(
+          item => item.value === event
+        );
+        // If there are no session items for this context, we should unsubscribe from the event.
+        if (!hasSessionItem) {
+          this.#unsubscribeEvent(event);
+        }
+      }
+
+      // Subscribe to all events, which have an item in SessionData.
+      for (const { value } of filteredSessionData) {
+        this.#subscribeEvent(value);
+      }
+    }
+  }
+}
+
+export const log = LogModule;
diff --git a/remote/webdriver-bidi/modules/windowglobal/script.sys.mjs b/remote/webdriver-bidi/modules/windowglobal/script.sys.mjs
new file mode 100644
index 0000000000..a2fa1fafc4
--- /dev/null
+++ b/remote/webdriver-bidi/modules/windowglobal/script.sys.mjs
@@ -0,0 +1,344 @@
+/* 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/. */
+
+import { Module } from "chrome://remote/content/shared/messagehandler/Module.sys.mjs";
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  deserialize: "chrome://remote/content/webdriver-bidi/RemoteValue.sys.mjs",
+  error: "chrome://remote/content/shared/webdriver/Errors.sys.mjs",
+  getFramesFromStack: "chrome://remote/content/shared/Stack.sys.mjs",
+  isChromeFrame: "chrome://remote/content/shared/Stack.sys.mjs",
+  serialize: "chrome://remote/content/webdriver-bidi/RemoteValue.sys.mjs",
+  stringify: "chrome://remote/content/webdriver-bidi/RemoteValue.sys.mjs",
+  WindowRealm: "chrome://remote/content/webdriver-bidi/Realm.sys.mjs",
+});
+
+/**
+ * @typedef {string} EvaluationStatus
+ **/
+
+/**
+ * Enum of possible evaluation states.
+ *
+ * @readonly
+ * @enum {EvaluationStatus}
+ **/
+const EvaluationStatus = {
+  Normal: "normal",
+  Throw: "throw",
+};
+
+class ScriptModule extends Module {
+  #defaultRealm;
+  #realms;
+
+  constructor(messageHandler) {
+    super(messageHandler);
+
+    this.#defaultRealm = new lazy.WindowRealm(this.messageHandler.window);
+
+    // Maps sandbox names to instances of window realms.
+    this.#realms = new Map();
+  }
+
+  destroy() {
+    this.#defaultRealm.destroy();
+
+    for (const realm of this.#realms.values()) {
+      realm.destroy();
+    }
+    this.#realms = null;
+  }
+
+  #buildExceptionDetails(exception, stack, realm, resultOwnership) {
+    exception = this.#toRawObject(exception);
+    const frames = lazy.getFramesFromStack(stack) || [];
+
+    const callFrames = frames
+      // Remove chrome/internal frames
+      .filter(frame => !lazy.isChromeFrame(frame))
+      // Translate frames from getFramesFromStack to frames expected by
+      // WebDriver BiDi.
+      .map(frame => {
+        return {
+          columnNumber: frame.columnNumber - 1,
+          functionName: frame.functionName,
+          lineNumber: frame.lineNumber - 1,
+          url: frame.filename,
+        };
+      });
+
+    return {
+      columnNumber: stack.column - 1,
+      exception: lazy.serialize(
+        exception,
+        1,
+        resultOwnership,
+        new Map(),
+        realm
+      ),
+      lineNumber: stack.line - 1,
+      stackTrace: { callFrames },
+      text: lazy.stringify(exception),
+    };
+  }
+
+  async #buildReturnValue(rv, realm, awaitPromise, resultOwnership) {
+    let evaluationStatus, exception, result, stack;
+
+    if ("return" in rv) {
+      evaluationStatus = EvaluationStatus.Normal;
+      if (
+        awaitPromise &&
+        // Only non-primitive return values are wrapped in Debugger.Object.
+        rv.return instanceof Debugger.Object &&
+        rv.return.isPromise
+      ) {
+        try {
+          // Force wrapping the promise resolution result in a Debugger.Object
+          // wrapper for consistency with the synchronous codepath.
+          const asyncResult = await rv.return.unsafeDereference();
+          result = realm.globalObjectReference.makeDebuggeeValue(asyncResult);
+        } catch (asyncException) {
+          evaluationStatus = EvaluationStatus.Throw;
+          exception = realm.globalObjectReference.makeDebuggeeValue(
+            asyncException
+          );
+          stack = rv.return.promiseResolutionSite;
+        }
+      } else {
+        // rv.return is a Debugger.Object or a primitive.
+        result = rv.return;
+      }
+    } else if ("throw" in rv) {
+      // rv.throw will be set if the evaluation synchronously failed, either if
+      // the script contains a syntax error or throws an exception.
+      evaluationStatus = EvaluationStatus.Throw;
+      exception = rv.throw;
+      stack = rv.stack;
+    }
+
+    switch (evaluationStatus) {
+      case EvaluationStatus.Normal:
+        return {
+          evaluationStatus,
+          result: lazy.serialize(
+            this.#toRawObject(result),
+            1,
+            resultOwnership,
+            new Map(),
+            realm
+          ),
+          realmId: realm.id,
+        };
+      case EvaluationStatus.Throw:
+        return {
+          evaluationStatus,
+          exceptionDetails: this.#buildExceptionDetails(
+            exception,
+            stack,
+            realm,
+            resultOwnership
+          ),
+          realmId: realm.id,
+        };
+      default:
+        throw new lazy.error.UnsupportedOperationError(
+          `Unsupported completion value for expression evaluation`
+        );
+    }
+  }
+
+  #getRealm(realmId, sandboxName) {
+    if (realmId === null) {
+      return this.#getRealmFromSandboxName(sandboxName);
+    }
+
+    if (this.#defaultRealm.id == realmId) {
+      return this.#defaultRealm;
+    }
+
+    const sandboxRealm = Array.from(this.#realms.values()).find(
+      realm => realm.id === realmId
+    );
+
+    if (sandboxRealm) {
+      return sandboxRealm;
+    }
+
+    throw new lazy.error.NoSuchFrameError(`Realm with id ${realmId} not found`);
+  }
+
+  #getRealmFromSandboxName(sandboxName) {
+    if (sandboxName === null || sandboxName === "") {
+      return this.#defaultRealm;
+    }
+
+    if (this.#realms.has(sandboxName)) {
+      return this.#realms.get(sandboxName);
+    }
+
+    const realm = new lazy.WindowRealm(this.messageHandler.window, {
+      sandboxName,
+    });
+
+    this.#realms.set(sandboxName, realm);
+
+    return realm;
+  }
+
+  #toRawObject(maybeDebuggerObject) {
+    if (maybeDebuggerObject instanceof Debugger.Object) {
+      // Retrieve the referent for the provided Debugger.object.
+      // See https://firefox-source-docs.mozilla.org/devtools-user/debugger-api/debugger.object/index.html
+      const rawObject = maybeDebuggerObject.unsafeDereference();
+
+      // TODO: Getters for Maps and Sets iterators return "Opaque" objects and
+      // are not iterable. RemoteValue.jsm' serializer should handle calling
+      // waiveXrays on Maps/Sets/... and then unwaiveXrays on entries but since
+      // we serialize with maxDepth=1, calling waiveXrays once on the root
+      // object allows to return correctly serialized values.
+      return Cu.waiveXrays(rawObject);
+    }
+
+    // If maybeDebuggerObject was not a Debugger.Object, it is a primitive value
+    // which can be used as is.
+    return maybeDebuggerObject;
+  }
+
+  /**
+   * Call a function in the current window global.
+   *
+   * @param {Object} options
+   * @param {boolean} awaitPromise
+   *     Determines if the command should wait for the return value of the
+   *     expression to resolve, if this return value is a Promise.
+   * @param {Array<RemoteValue>=} commandArguments
+   *     The arguments to pass to the function call.
+   * @param {string} functionDeclaration
+   *     The body of the function to call.
+   * @param {string=} realmId
+   *     The id of the realm.
+   * @param {OwnershipModel} resultOwnership
+   *     The ownership model to use for the results of this evaluation.
+   * @param {string=} sandbox
+   *     The name of the sandbox.
+   * @param {RemoteValue=} thisParameter
+   *     The value of the this keyword for the function call.
+   *
+   * @return {Object}
+   *     - evaluationStatus {EvaluationStatus} One of "normal", "throw".
+   *     - exceptionDetails {ExceptionDetails=} the details of the exception if
+   *     the evaluation status was "throw".
+   *     - result {RemoteValue=} the result of the evaluation serialized as a
+   *     RemoteValue if the evaluation status was "normal".
+   */
+  async callFunctionDeclaration(options) {
+    const {
+      awaitPromise,
+      commandArguments = null,
+      functionDeclaration,
+      realmId = null,
+      resultOwnership,
+      sandbox: sandboxName = null,
+      thisParameter = null,
+    } = options;
+
+    const realm = this.#getRealm(realmId, sandboxName);
+
+    const deserializedArguments =
+      commandArguments !== null
+        ? commandArguments.map(arg => lazy.deserialize(realm, arg))
+        : [];
+
+    const deserializedThis =
+      thisParameter !== null ? lazy.deserialize(realm, thisParameter) : null;
+
+    const rv = realm.executeInGlobalWithBindings(
+      functionDeclaration,
+      deserializedArguments,
+      deserializedThis
+    );
+
+    return this.#buildReturnValue(rv, realm, awaitPromise, resultOwnership);
+  }
+
+  /**
+   * Delete the provided handles from the realm corresponding to the provided
+   * sandbox name.
+   *
+   * @param {Object=} options
+   * @param {Array<string>} handles
+   *     Array of handle ids to disown.
+   * @param {string=} realmId
+   *     The id of the realm.
+   * @param {string=} sandbox
+   *     The name of the sandbox.
+   */
+  disownHandles(options) {
+    const { handles, realmId = null, sandbox: sandboxName = null } = options;
+    const realm = this.#getRealm(realmId, sandboxName);
+    for (const handle of handles) {
+      realm.removeObjectHandle(handle);
+    }
+  }
+
+  /**
+   * Evaluate a provided expression in the current window global.
+   *
+   * @param {Object} options
+   * @param {boolean} awaitPromise
+   *     Determines if the command should wait for the return value of the
+   *     expression to resolve, if this return value is a Promise.
+   * @param {string} expression
+   *     The expression to evaluate.
+   * @param {string=} realmId
+   *     The id of the realm.
+   * @param {OwnershipModel} resultOwnership
+   *     The ownership model to use for the results of this evaluation.
+   * @param {string=} sandbox
+   *     The name of the sandbox.
+   *
+   * @return {Object}
+   *     - evaluationStatus {EvaluationStatus} One of "normal", "throw".
+   *     - exceptionDetails {ExceptionDetails=} the details of the exception if
+   *     the evaluation status was "throw".
+   *     - result {RemoteValue=} the result of the evaluation serialized as a
+   *     RemoteValue if the evaluation status was "normal".
+   */
+  async evaluateExpression(options) {
+    const {
+      awaitPromise,
+      expression,
+      realmId = null,
+      resultOwnership,
+      sandbox: sandboxName = null,
+    } = options;
+
+    const realm = this.#getRealm(realmId, sandboxName);
+    const rv = realm.executeInGlobal(expression);
+
+    return this.#buildReturnValue(rv, realm, awaitPromise, resultOwnership);
+  }
+
+  /**
+   * Get realms for the current window global.
+   *
+   * @return {Array<Object>}
+   *     - context {BrowsingContext} The browsing context, associated with the realm.
+   *     - id {string} The realm unique identifier.
+   *     - origin {string} The serialization of an origin.
+   *     - sandbox {string=} The name of the sandbox.
+   *     - type {RealmType.Window} The window realm type.
+   */
+  getWindowRealms() {
+    return [this.#defaultRealm, ...this.#realms.values()].map(realm =>
+      realm.getInfo()
+    );
+  }
+}
+
+export const script = ScriptModule;
diff --git a/remote/webdriver-bidi/moz.build b/remote/webdriver-bidi/moz.build
new file mode 100644
index 0000000000..3c13a0ac11
--- /dev/null
+++ b/remote/webdriver-bidi/moz.build
@@ -0,0 +1,10 @@
+# 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/.
+
+JAR_MANIFESTS += ["jar.mn"]
+
+with Files("**"):
+    BUG_COMPONENT = ("Remote Protocol", "WebDriver BiDi")
+
+XPCSHELL_TESTS_MANIFESTS += ["test/xpcshell/xpcshell.ini"]
diff --git a/remote/webdriver-bidi/test/xpcshell/test_Realm.js b/remote/webdriver-bidi/test/xpcshell/test_Realm.js
new file mode 100644
index 0000000000..ff39adcd82
--- /dev/null
+++ b/remote/webdriver-bidi/test/xpcshell/test_Realm.js
@@ -0,0 +1,90 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { Realm } = ChromeUtils.importESModule(
+  "chrome://remote/content/webdriver-bidi/Realm.sys.mjs"
+);
+
+add_test(function test_id() {
+  const realm1 = new Realm();
+  const id1 = realm1.id;
+  Assert.equal(typeof id1, "string");
+
+  const realm2 = new Realm();
+  const id2 = realm2.id;
+  Assert.equal(typeof id2, "string");
+
+  Assert.notEqual(id1, id2, "Ids for different realms are different");
+
+  run_next_test();
+});
+
+add_test(function test_handleObjectMap() {
+  const realm = new Realm();
+
+  // Test an unknown handle.
+  Assert.equal(
+    realm.getObjectForHandle("unknown"),
+    undefined,
+    "Unknown handles return undefined"
+  );
+
+  // Test creating a simple handle.
+  const object = {};
+  const handle = realm.getHandleForObject(object);
+  Assert.equal(typeof handle, "string", "Created a valid handle");
+  Assert.equal(
+    realm.getObjectForHandle(handle),
+    object,
+    "Using the handle returned the original object"
+  );
+
+  // Test another handle for the same object.
+  const secondHandle = realm.getHandleForObject(object);
+  Assert.equal(typeof secondHandle, "string", "Created a valid handle");
+  Assert.notEqual(secondHandle, handle, "A different handle was generated");
+  Assert.equal(
+    realm.getObjectForHandle(secondHandle),
+    object,
+    "Using the second handle also returned the original object"
+  );
+
+  // Test using the handles in another realm.
+  const otherRealm = new Realm();
+  Assert.equal(
+    otherRealm.getObjectForHandle(handle),
+    undefined,
+    "A realm returns undefined for handles from another realm"
+  );
+
+  // Removing an unknown handle should not throw or have any side effect on
+  // existing handles.
+  realm.removeObjectHandle("unknown");
+  Assert.equal(realm.getObjectForHandle(handle), object);
+  Assert.equal(realm.getObjectForHandle(secondHandle), object);
+
+  // Remove the second handle
+  realm.removeObjectHandle(secondHandle);
+  Assert.equal(
+    realm.getObjectForHandle(handle),
+    object,
+    "The first handle is still resolving the object"
+  );
+  Assert.equal(
+    realm.getObjectForHandle(secondHandle),
+    undefined,
+    "The second handle returns undefined after calling removeObjectHandle"
+  );
+
+  // Remove the original handle
+  realm.removeObjectHandle(handle);
+  Assert.equal(
+    realm.getObjectForHandle(handle),
+    undefined,
+    "The first handle returns undefined as well"
+  );
+
+  run_next_test();
+});
diff --git a/remote/webdriver-bidi/test/xpcshell/test_RemoteValue.js b/remote/webdriver-bidi/test/xpcshell/test_RemoteValue.js
new file mode 100644
index 0000000000..8147711417
--- /dev/null
+++ b/remote/webdriver-bidi/test/xpcshell/test_RemoteValue.js
@@ -0,0 +1,1016 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const browser = Services.appShell.createWindowlessBrowser(false);
+const domEl = browser.document.createElement("div");
+browser.document.body.appendChild(domEl);
+
+const PRIMITIVE_TYPES = [
+  { value: undefined, serialized: { type: "undefined" } },
+  { value: null, serialized: { type: "null" } },
+  { value: "foo", serialized: { type: "string", value: "foo" } },
+  { value: Number.NaN, serialized: { type: "number", value: "NaN" } },
+  { value: -0, serialized: { type: "number", value: "-0" } },
+  {
+    value: Number.POSITIVE_INFINITY,
+    serialized: { type: "number", value: "Infinity" },
+  },
+  {
+    value: Number.NEGATIVE_INFINITY,
+    serialized: { type: "number", value: "-Infinity" },
+  },
+  { value: 42, serialized: { type: "number", value: 42 } },
+  { value: false, serialized: { type: "boolean", value: false } },
+  { value: 42n, serialized: { type: "bigint", value: "42" } },
+];
+
+const REMOTE_SIMPLE_VALUES = [
+  {
+    value: new RegExp(/foo/),
+    serialized: {
+      type: "regexp",
+      value: {
+        pattern: "foo",
+        flags: "",
+      },
+    },
+    deserializable: true,
+  },
+  {
+    value: new RegExp(/foo/g),
+    serialized: {
+      type: "regexp",
+      value: {
+        pattern: "foo",
+        flags: "g",
+      },
+    },
+    deserializable: true,
+  },
+  {
+    value: new Date(1654004849000),
+    serialized: {
+      type: "date",
+      value: "2022-05-31T13:47:29.000Z",
+    },
+    deserializable: true,
+  },
+];
+
+const REMOTE_COMPLEX_VALUES = [
+  { value: Symbol("foo"), serialized: { type: "symbol" } },
+  {
+    value: [1],
+    serialized: {
+      type: "array",
+    },
+  },
+  {
+    value: [1],
+    maxDepth: 0,
+    serialized: {
+      type: "array",
+    },
+  },
+  {
+    value: [1, "2", true, new RegExp(/foo/g)],
+    maxDepth: 1,
+    serialized: {
+      type: "array",
+      value: [
+        { type: "number", value: 1 },
+        { type: "string", value: "2" },
+        { type: "boolean", value: true },
+        {
+          type: "regexp",
+          value: {
+            pattern: "foo",
+            flags: "g",
+          },
+        },
+      ],
+    },
+    deserializable: true,
+  },
+  {
+    value: [1, [3, "4"]],
+    maxDepth: 1,
+    serialized: {
+      type: "array",
+      value: [{ type: "number", value: 1 }, { type: "array" }],
+    },
+  },
+  {
+    value: [1, [3, "4"]],
+    maxDepth: 2,
+    serialized: {
+      type: "array",
+      value: [
+        { type: "number", value: 1 },
+        {
+          type: "array",
+          value: [
+            { type: "number", value: 3 },
+            { type: "string", value: "4" },
+          ],
+        },
+      ],
+    },
+    deserializable: true,
+  },
+  {
+    value: new Map(),
+    maxDepth: 1,
+    serialized: {
+      type: "map",
+      value: [],
+    },
+    deserializable: true,
+  },
+  {
+    value: new Map([]),
+    maxDepth: 1,
+    serialized: {
+      type: "map",
+      value: [],
+    },
+    deserializable: true,
+  },
+  {
+    value: new Map([
+      [1, 2],
+      ["2", "3"],
+      [true, false],
+    ]),
+    serialized: {
+      type: "map",
+    },
+  },
+  {
+    value: new Map([
+      [1, 2],
+      ["2", "3"],
+      [true, false],
+    ]),
+    maxDepth: 0,
+    serialized: {
+      type: "map",
+    },
+  },
+  {
+    value: new Map([
+      [1, 2],
+      ["2", "3"],
+      [true, false],
+    ]),
+    maxDepth: 1,
+    serialized: {
+      type: "map",
+      value: [
+        [
+          { type: "number", value: 1 },
+          { type: "number", value: 2 },
+        ],
+        ["2", { type: "string", value: "3" }],
+        [
+          { type: "boolean", value: true },
+          { type: "boolean", value: false },
+        ],
+      ],
+    },
+    deserializable: true,
+  },
+  {
+    value: new Set(),
+    maxDepth: 1,
+    serialized: {
+      type: "set",
+      value: [],
+    },
+    deserializable: true,
+  },
+  {
+    value: new Set([]),
+    maxDepth: 1,
+    serialized: {
+      type: "set",
+      value: [],
+    },
+    deserializable: true,
+  },
+  {
+    value: new Set([1, "2", true]),
+    serialized: {
+      type: "set",
+    },
+  },
+  {
+    value: new Set([1, "2", true]),
+    maxDepth: 0,
+    serialized: {
+      type: "set",
+    },
+  },
+  {
+    value: new Set([1, "2", true]),
+    maxDepth: 1,
+    serialized: {
+      type: "set",
+      value: [
+        { type: "number", value: 1 },
+        { type: "string", value: "2" },
+        { type: "boolean", value: true },
+      ],
+    },
+    deserializable: true,
+  },
+  { value: new WeakMap([[{}, 1]]), serialized: { type: "weakmap" } },
+  { value: new WeakSet([{}]), serialized: { type: "weakset" } },
+  { value: new Error("error message"), serialized: { type: "error" } },
+  {
+    value: new SyntaxError("syntax error message"),
+    serialized: { type: "error" },
+  },
+  {
+    value: new TypeError("type error message"),
+    serialized: { type: "error" },
+  },
+  { value: new Promise(() => true), serialized: { type: "promise" } },
+  { value: new Int8Array(), serialized: { type: "typedarray" } },
+  { value: new ArrayBuffer(), serialized: { type: "arraybuffer" } },
+  {
+    value: browser.document.querySelectorAll("div"),
+    serialized: { type: "nodelist" },
+  },
+  {
+    value: browser.document.getElementsByTagName("div"),
+    serialized: { type: "htmlcollection" },
+  },
+  {
+    value: domEl,
+    serialized: {
+      type: "node",
+      value: {
+        attributes: {},
+        childNodeCount: 0,
+        children: [],
+        localName: "div",
+        namespaceURI: "http://www.w3.org/1999/xhtml",
+        nodeType: 1,
+      },
+    },
+  },
+  { value: browser.document.defaultView, serialized: { type: "window" } },
+  { value: new URL("https://example.com"), serialized: { type: "object" } },
+  { value: () => true, serialized: { type: "function" } },
+  { value() {}, serialized: { type: "function" } },
+  {
+    value: {},
+    maxDepth: 1,
+    serialized: {
+      type: "object",
+      value: [],
+    },
+    deserializable: true,
+  },
+  {
+    value: {
+      "1": 1,
+      "2": "2",
+      foo: true,
+    },
+    serialized: {
+      type: "object",
+    },
+  },
+  {
+    value: {
+      "1": 1,
+      "2": "2",
+      foo: true,
+    },
+    maxDepth: 0,
+    serialized: {
+      type: "object",
+    },
+  },
+  {
+    value: {
+      "1": 1,
+      "2": "2",
+      foo: true,
+    },
+    maxDepth: 1,
+    serialized: {
+      type: "object",
+      value: [
+        ["1", { type: "number", value: 1 }],
+        ["2", { type: "string", value: "2" }],
+        ["foo", { type: "boolean", value: true }],
+      ],
+    },
+    deserializable: true,
+  },
+  {
+    value: {
+      "1": 1,
+      "2": "2",
+      "3": {
+        bar: "foo",
+      },
+      foo: true,
+    },
+    maxDepth: 2,
+    serialized: {
+      type: "object",
+      value: [
+        ["1", { type: "number", value: 1 }],
+        ["2", { type: "string", value: "2" }],
+        [
+          "3",
+          {
+            type: "object",
+            value: [["bar", { type: "string", value: "foo" }]],
+          },
+        ],
+        ["foo", { type: "boolean", value: true }],
+      ],
+    },
+    deserializable: true,
+  },
+];
+
+const { Realm } = ChromeUtils.importESModule(
+  "chrome://remote/content/webdriver-bidi/Realm.sys.mjs"
+);
+
+const { deserialize, serialize, stringify } = ChromeUtils.importESModule(
+  "chrome://remote/content/webdriver-bidi/RemoteValue.sys.mjs"
+);
+
+add_test(function test_deserializePrimitiveTypes() {
+  const realm = new Realm();
+
+  for (const type of PRIMITIVE_TYPES) {
+    const { value: expectedValue, serialized } = type;
+
+    info(`Checking '${serialized.type}'`);
+    const value = deserialize(realm, serialized);
+
+    if (serialized.value == "NaN") {
+      ok(Number.isNaN(value), `Got expected value for ${serialized}`);
+    } else {
+      Assert.strictEqual(
+        value,
+        expectedValue,
+        `Got expected value for ${serialized}`
+      );
+    }
+  }
+
+  run_next_test();
+});
+
+add_test(function test_deserializeDateLocalValue() {
+  const realm = new Realm();
+
+  const validaDateStrings = [
+    "2009",
+    "2009-05",
+    "2009-05-19",
+    "2009T15:00",
+    "2009-05T15:00",
+    "2009-05-19T15:00",
+    "2009-05-19T15:00:15",
+    "2009-05-19T15:00:15.452",
+    "2009-05-19T15:00:15.452Z",
+    "2009-05-19T15:00:15.452+02:00",
+    "2009-05-19T15:00:15.452-02:00",
+    "-271821-04-20T00:00:00Z",
+    "+000000-01-01T00:00:00Z",
+  ];
+  for (const dateString of validaDateStrings) {
+    info(`Checking '${dateString}'`);
+    const value = deserialize(realm, { type: "date", value: dateString });
+
+    Assert.equal(
+      value.getTime(),
+      new Date(dateString).getTime(),
+      `Got expected value for ${dateString}`
+    );
+  }
+
+  run_next_test();
+});
+
+add_test(function test_deserializeLocalValues() {
+  const realm = new Realm();
+
+  for (const type of REMOTE_SIMPLE_VALUES.concat(REMOTE_COMPLEX_VALUES)) {
+    const { value: expectedValue, serialized, deserializable } = type;
+
+    // Skip non deserializable cases
+    if (!deserializable) {
+      continue;
+    }
+
+    info(`Checking '${serialized.type}'`);
+    const value = deserialize(realm, serialized);
+    assertLocalValue(serialized.type, value, expectedValue);
+  }
+
+  run_next_test();
+});
+
+add_test(function test_deserializeLocalValuesByHandle() {
+  // Create two realms, realm1 will be used to serialize values, while realm2
+  // will be used as a reference empty realm without any object reference.
+  const realm1 = new Realm();
+  const realm2 = new Realm();
+
+  for (const type of REMOTE_SIMPLE_VALUES.concat(REMOTE_COMPLEX_VALUES)) {
+    const { value: expectedValue, serialized } = type;
+
+    // No need to skip non-deserializable cases here.
+
+    info(`Checking '${serialized.type}'`);
+    // Serialize the value once to get a handle.
+    const serializedValue = serialize(
+      expectedValue,
+      0,
+      "root",
+      new Map(),
+      realm1
+    );
+
+    // Create a remote reference containing only the handle.
+    // `deserialize` should not need any other property.
+    const remoteReference = { handle: serializedValue.handle };
+
+    // Check that the remote reference can be deserialized in realm1.
+    const deserializedValue = deserialize(realm1, remoteReference);
+    assertLocalValue(serialized.type, deserializedValue, expectedValue);
+
+    Assert.throws(
+      () => deserialize(realm2, remoteReference),
+      /InvalidArgumentError:/,
+      `Got expected error when using the wrong realm for deserialize`
+    );
+
+    realm1.removeObjectHandle(serializedValue.handle);
+    Assert.throws(
+      () => deserialize(realm1, remoteReference),
+      /InvalidArgumentError:/,
+      `Got expected error when after deleting the object handle`
+    );
+  }
+
+  run_next_test();
+});
+
+add_test(function test_deserializePrimitiveTypesInvalidValues() {
+  const realm = new Realm();
+
+  const invalidValues = [
+    { type: "bigint", values: [undefined, null, false, "foo", [], {}] },
+    { type: "boolean", values: [undefined, null, 42, "foo", [], {}] },
+    {
+      type: "number",
+      values: [undefined, null, false, "43", [], {}],
+    },
+    { type: "string", values: [undefined, null, false, 42, [], {}] },
+  ];
+
+  for (const invalidValue of invalidValues) {
+    const { type, values } = invalidValue;
+
+    for (const value of values) {
+      info(`Checking '${type}' with value ${value}`);
+
+      Assert.throws(
+        () => deserialize(realm, { type, value }),
+        /InvalidArgument/,
+        `Got expected error for type ${type} and value ${value}`
+      );
+    }
+  }
+
+  run_next_test();
+});
+
+add_test(function test_deserializeDateLocalValueInvalidValues() {
+  const realm = new Realm();
+
+  const invalidaDateStrings = [
+    "10",
+    "20009",
+    "+20009",
+    "2009-",
+    "2009-0",
+    "2009-15",
+    "2009-02-1",
+    "2009-02-50",
+    "2022-02-29",
+    "15:00",
+    "T15:00",
+    "9-05-19T15:00",
+    "2009-5-19T15:00",
+    "2009-05-1T15:00",
+    "2009-02-10T15",
+    "2009-05-19T15:",
+    "2009-05-19T1:00",
+    "2009-05-19T10:1",
+    "2022-06-31T15:00",
+    "2009-05-19T60:00",
+    "2009-05-19T15:70",
+    "2009-05-19T15:00.25",
+    "2009-05-19+10:00",
+    "2009-05-19Z",
+    "2009-05-19 15:00",
+    "2009-05-19t15:00Z",
+    "2009-05-19T15:00z",
+    "2009-05-19T15:00+01",
+    "2009-05-19T10:10+1:00",
+    "2009-05-19T10:10+01:1",
+    "2009-05-19T15:00+75:00",
+    "2009-05-19T15:00+02:80",
+    "2009-05-19T15:00-00:00",
+    "02009-05-19T15:00",
+  ];
+  for (const dateString of invalidaDateStrings) {
+    info(`Checking '${dateString}'`);
+
+    Assert.throws(
+      () => deserialize(realm, { type: "date", value: dateString }),
+      /InvalidArgumentError:/,
+      `Got expected error for date string: ${dateString}`
+    );
+  }
+
+  run_next_test();
+});
+
+add_test(function test_deserializeLocalValuesInvalidType() {
+  const realm = new Realm();
+
+  const invalidTypes = [undefined, null, false, 42, {}];
+
+  for (const invalidType of invalidTypes) {
+    info(`Checking type: '${invalidType}'`);
+
+    Assert.throws(
+      () => deserialize(realm, { type: invalidType }),
+      /InvalidArgumentError:/,
+      `Got expected error for type ${invalidType}`
+    );
+
+    Assert.throws(
+      () =>
+        deserialize(realm, {
+          type: "array",
+          value: [{ type: invalidType }],
+        }),
+      /InvalidArgumentError:/,
+      `Got expected error for nested type ${invalidType}`
+    );
+  }
+
+  run_next_test();
+});
+
+add_test(function test_deserializeLocalValuesInvalidValues() {
+  const realm = new Realm();
+
+  const invalidValues = [
+    { type: "array", values: [undefined, null, false, 42, "foo", {}] },
+    {
+      type: "regexp",
+      values: [
+        undefined,
+        null,
+        false,
+        "foo",
+        42,
+        [],
+        {},
+        { pattern: null },
+        { pattern: 1 },
+        { pattern: true },
+        { pattern: "foo", flags: null },
+        { pattern: "foo", flags: 1 },
+        { pattern: "foo", flags: false },
+        { pattern: "foo", flags: "foo" },
+      ],
+    },
+    {
+      type: "date",
+      values: [
+        undefined,
+        null,
+        false,
+        "foo",
+        "05 October 2011 14:48 UTC",
+        "Tue Jun 14 2022 10:46:50 GMT+0200!",
+        42,
+        [],
+        {},
+      ],
+    },
+    {
+      type: "map",
+      values: [
+        undefined,
+        null,
+        false,
+        "foo",
+        42,
+        ["1"],
+        [[]],
+        [["1"]],
+        [{ "1": "2" }],
+        {},
+      ],
+    },
+    {
+      type: "set",
+      values: [undefined, null, false, "foo", 42, {}],
+    },
+    {
+      type: "object",
+      values: [
+        undefined,
+        null,
+        false,
+        "foo",
+        42,
+        {},
+        ["1"],
+        [[]],
+        [["1"]],
+        [{ "1": "2" }],
+        [
+          [
+            { type: "number", value: "1" },
+            { type: "number", value: "2" },
+          ],
+        ],
+        [
+          [
+            { type: "object", value: [] },
+            { type: "number", value: "1" },
+          ],
+        ],
+        [
+          [
+            {
+              type: "regexp",
+              value: {
+                pattern: "foo",
+              },
+            },
+            { type: "number", value: "1" },
+          ],
+        ],
+      ],
+    },
+  ];
+
+  for (const invalidValue of invalidValues) {
+    const { type, values } = invalidValue;
+
+    for (const value of values) {
+      info(`Checking '${type}' with value ${value}`);
+
+      Assert.throws(
+        () => deserialize(realm, { type, value }),
+        /InvalidArgumentError:/,
+        `Got expected error for type ${type} and value ${value}`
+      );
+    }
+  }
+
+  run_next_test();
+});
+
+add_test(function test_serializePrimitiveTypes() {
+  const realm = new Realm();
+
+  for (const type of PRIMITIVE_TYPES) {
+    const { value, serialized } = type;
+
+    const serializationInternalMap = new Map();
+    const serializedValue = serialize(
+      value,
+      0,
+      "none",
+      serializationInternalMap,
+      realm
+    );
+    assertInternalIds(serializationInternalMap, 0);
+    Assert.deepEqual(serialized, serializedValue, "Got expected structure");
+
+    // For primitive values, the serialization with ownershipType=root should
+    // be exactly identical to the one with ownershipType=none.
+    const serializationInternalMapWithRoot = new Map();
+    const serializedWithRoot = serialize(
+      value,
+      0,
+      "root",
+      serializationInternalMapWithRoot,
+      realm
+    );
+    assertInternalIds(serializationInternalMapWithRoot, 0);
+    Assert.deepEqual(serialized, serializedWithRoot, "Got expected structure");
+  }
+
+  run_next_test();
+});
+
+add_test(function test_serializeRemoteSimpleValues() {
+  const realm = new Realm();
+
+  for (const type of REMOTE_SIMPLE_VALUES) {
+    const { value, serialized } = type;
+
+    info(`Checking '${serialized.type}' with none ownershipType`);
+    const serializationInternalMapWithNone = new Map();
+    const serializedValue = serialize(
+      value,
+      0,
+      "none",
+      serializationInternalMapWithNone,
+      realm
+    );
+
+    assertInternalIds(serializationInternalMapWithNone, 0);
+    Assert.deepEqual(serialized, serializedValue, "Got expected structure");
+
+    info(`Checking '${serialized.type}' with root ownershipType`);
+    const serializationInternalMapWithRoot = new Map();
+    const serializedWithRoot = serialize(
+      value,
+      0,
+      "root",
+      serializationInternalMapWithRoot,
+      realm
+    );
+
+    assertInternalIds(serializationInternalMapWithRoot, 0);
+    Assert.equal(
+      typeof serializedWithRoot.handle,
+      "string",
+      "Got a handle property"
+    );
+    Assert.deepEqual(
+      Object.assign({}, serialized, { handle: serializedWithRoot.handle }),
+      serializedWithRoot,
+      "Got expected structure, plus a generated handle id"
+    );
+  }
+
+  run_next_test();
+});
+
+add_test(function test_serializeRemoteComplexValues() {
+  const realm = new Realm();
+
+  for (const type of REMOTE_COMPLEX_VALUES) {
+    const { value, serialized, maxDepth } = type;
+
+    info(`Checking '${serialized.type}' with none ownershipType`);
+    const serializationInternalMapWithNone = new Map();
+    const serializedValue = serialize(
+      value,
+      maxDepth,
+      "none",
+      serializationInternalMapWithNone,
+      realm
+    );
+
+    assertInternalIds(serializationInternalMapWithNone, 0);
+    Assert.deepEqual(serialized, serializedValue, "Got expected structure");
+
+    info(`Checking '${serialized.type}' with root ownershipType`);
+    const serializationInternalMapWithRoot = new Map();
+    const serializedWithRoot = serialize(
+      value,
+      maxDepth,
+      "root",
+      serializationInternalMapWithRoot,
+      realm
+    );
+
+    assertInternalIds(serializationInternalMapWithRoot, 0);
+    Assert.equal(
+      typeof serializedWithRoot.handle,
+      "string",
+      "Got a handle property"
+    );
+    Assert.deepEqual(
+      Object.assign({}, serialized, { handle: serializedWithRoot.handle }),
+      serializedWithRoot,
+      "Got expected structure, plus a generated handle id"
+    );
+  }
+
+  run_next_test();
+});
+
+add_test(function test_serializeWithSerializationInternalMap() {
+  const dataSet = [
+    {
+      data: [1],
+      serializedData: [{ type: "number", value: 1 }],
+      type: "array",
+    },
+    {
+      data: new Map([[true, false]]),
+      serializedData: [
+        [
+          { type: "boolean", value: true },
+          { type: "boolean", value: false },
+        ],
+      ],
+      type: "map",
+    },
+    {
+      data: new Set(["foo"]),
+      serializedData: [{ type: "string", value: "foo" }],
+      type: "set",
+    },
+    {
+      data: { foo: "bar" },
+      serializedData: [["foo", { type: "string", value: "bar" }]],
+      type: "object",
+    },
+  ];
+  const realm = new Realm();
+
+  for (const { type, data, serializedData } of dataSet) {
+    info(`Checking '${type}' with serializationInternalMap`);
+
+    const serializationInternalMap = new Map();
+    const value = [
+      data,
+      data,
+      [data],
+      new Set([data]),
+      new Map([["bar", data]]),
+      { bar: data },
+    ];
+
+    const serializedValue = serialize(
+      value,
+      2,
+      "none",
+      serializationInternalMap,
+      realm
+    );
+
+    assertInternalIds(serializationInternalMap, 1);
+
+    const internalId = serializationInternalMap.get(data).internalId;
+
+    const serialized = {
+      type: "array",
+      value: [
+        {
+          type,
+          value: serializedData,
+          internalId,
+        },
+        {
+          type,
+          internalId,
+        },
+        {
+          type: "array",
+          value: [{ type, internalId }],
+        },
+        {
+          type: "set",
+          value: [{ type, internalId }],
+        },
+        {
+          type: "map",
+          value: [["bar", { type, internalId }]],
+        },
+        {
+          type: "object",
+          value: [["bar", { type, internalId }]],
+        },
+      ],
+    };
+
+    Assert.deepEqual(serialized, serializedValue, "Got expected structure");
+  }
+
+  run_next_test();
+});
+
+add_test(function test_serializeMultipleValuesWithSerializationInternalMap() {
+  const realm = new Realm();
+  const serializationInternalMap = new Map();
+  const obj1 = { foo: "bar" };
+  const obj2 = [1, 2];
+  const value = [obj1, obj2, obj1, obj2];
+
+  serialize(value, 2, "none", serializationInternalMap, realm);
+
+  assertInternalIds(serializationInternalMap, 2);
+
+  const internalId1 = serializationInternalMap.get(obj1).internalId;
+  const internalId2 = serializationInternalMap.get(obj2).internalId;
+
+  Assert.notEqual(
+    internalId1,
+    internalId2,
+    "Internal ids for different object are also different"
+  );
+
+  run_next_test();
+});
+
+add_test(function test_stringify() {
+  const STRINGIFY_TEST_CASES = [
+    [undefined, "undefined"],
+    [null, "null"],
+    ["foobar", "foobar"],
+    ["2", "2"],
+    [-0, "0"],
+    [Infinity, "Infinity"],
+    [-Infinity, "-Infinity"],
+    [3, "3"],
+    [1.4, "1.4"],
+    [true, "true"],
+    [42n, "42"],
+    [{ toString: () => "bar" }, "bar", "toString: () => 'bar'"],
+    [{ toString: () => 4 }, "[object Object]", "toString: () => 4"],
+    [{ toString: undefined }, "[object Object]", "toString: undefined"],
+    [{ toString: null }, "[object Object]", "toString: null"],
+    [
+      {
+        toString: () => {
+          throw new Error("toString error");
+        },
+      },
+      "[object Object]",
+      "toString: () => { throw new Error('toString error'); }",
+    ],
+  ];
+
+  for (const [value, expectedString, description] of STRINGIFY_TEST_CASES) {
+    info(`Checking '${description || value}'`);
+    const stringifiedValue = stringify(value);
+
+    Assert.strictEqual(expectedString, stringifiedValue, "Got expected string");
+  }
+
+  run_next_test();
+});
+
+function assertLocalValue(type, value, expectedValue) {
+  let formattedValue = value;
+  let formattedExpectedValue = expectedValue;
+
+  // Format certain types for easier assertion
+  if (type == "map") {
+    Assert.equal(
+      Object.prototype.toString.call(expectedValue),
+      "[object Map]",
+      "Got expected type Map"
+    );
+
+    formattedValue = Array.from(value.values());
+    formattedExpectedValue = Array.from(expectedValue.values());
+  } else if (type == "set") {
+    Assert.equal(
+      Object.prototype.toString.call(expectedValue),
+      "[object Set]",
+      "Got expected type Set"
+    );
+
+    formattedValue = Array.from(value);
+    formattedExpectedValue = Array.from(expectedValue);
+  }
+
+  Assert.deepEqual(
+    formattedValue,
+    formattedExpectedValue,
+    "Got expected structure"
+  );
+}
+
+function assertInternalIds(serializationInternalMap, amount) {
+  const remoteValuesWithInternalIds = Array.from(
+    serializationInternalMap.values()
+  ).filter(remoteValue => !!remoteValue.internalId);
+
+  Assert.equal(
+    remoteValuesWithInternalIds.length,
+    amount,
+    "Got expected amount of internalIds in serializationInternalMap"
+  );
+}
diff --git a/remote/webdriver-bidi/test/xpcshell/test_WebDriverBiDiConnection.js b/remote/webdriver-bidi/test/xpcshell/test_WebDriverBiDiConnection.js
new file mode 100644
index 0000000000..10b43e4ed6
--- /dev/null
+++ b/remote/webdriver-bidi/test/xpcshell/test_WebDriverBiDiConnection.js
@@ -0,0 +1,27 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { splitMethod } = ChromeUtils.importESModule(
+  "chrome://remote/content/webdriver-bidi/WebDriverBiDiConnection.sys.mjs"
+);
+
+add_test(function test_Connection_splitMethod() {
+  for (const t of [42, null, true, {}, [], undefined]) {
+    Assert.throws(() => splitMethod(t), /TypeError/, `${typeof t} throws`);
+  }
+  for (const s of ["", ".", "foo.", ".bar", "foo.bar.baz"]) {
+    Assert.throws(
+      () => splitMethod(s),
+      /Invalid method format: '.*'/,
+      `"${s}" throws`
+    );
+  }
+  deepEqual(splitMethod("foo.bar"), {
+    module: "foo",
+    command: "bar",
+  });
+
+  run_next_test();
+});
diff --git a/remote/webdriver-bidi/test/xpcshell/xpcshell.ini b/remote/webdriver-bidi/test/xpcshell/xpcshell.ini
new file mode 100644
index 0000000000..8873ae646d
--- /dev/null
+++ b/remote/webdriver-bidi/test/xpcshell/xpcshell.ini
@@ -0,0 +1,7 @@
+# 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/.
+
+[test_Realm.js]
+[test_RemoteValue.js]
+[test_WebDriverBiDiConnection.js]