Adding upstream version 124.0.1.upstream/124.0.1

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

1 files changed, 3942 insertions, 0 deletions

diff --git a/toolkit/components/extensions/Schemas.sys.mjs b/toolkit/components/extensions/Schemas.sys.mjs
new file mode 100644
index 0000000000..9107e6a347
--- /dev/null
+++ b/toolkit/components/extensions/Schemas.sys.mjs
@@ -0,0 +1,3942 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+/* 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 { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
+
+import { ExtensionUtils } from "resource://gre/modules/ExtensionUtils.sys.mjs";
+
+var { DefaultMap, DefaultWeakMap } = ExtensionUtils;
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  ExtensionParent: "resource://gre/modules/ExtensionParent.sys.mjs",
+  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
+  ShortcutUtils: "resource://gre/modules/ShortcutUtils.sys.mjs",
+});
+
+XPCOMUtils.defineLazyServiceGetter(
+  lazy,
+  "contentPolicyService",
+  "@mozilla.org/addons/content-policy;1",
+  "nsIAddonContentPolicy"
+);
+
+ChromeUtils.defineLazyGetter(
+  lazy,
+  "StartupCache",
+  () => lazy.ExtensionParent.StartupCache
+);
+
+XPCOMUtils.defineLazyPreferenceGetter(
+  lazy,
+  "treatWarningsAsErrors",
+  "extensions.webextensions.warnings-as-errors",
+  false
+);
+
+const KEY_CONTENT_SCHEMAS = "extensions-framework/schemas/content";
+const KEY_PRIVILEGED_SCHEMAS = "extensions-framework/schemas/privileged";
+
+const MIN_MANIFEST_VERSION = 2;
+const MAX_MANIFEST_VERSION = 3;
+
+const { DEBUG } = AppConstants;
+
+const isParentProcess =
+  Services.appinfo.processType === Services.appinfo.PROCESS_TYPE_DEFAULT;
+
+function readJSON(url) {
+  return new Promise((resolve, reject) => {
+    lazy.NetUtil.asyncFetch(
+      { uri: url, loadUsingSystemPrincipal: true },
+      (inputStream, status) => {
+        if (!Components.isSuccessCode(status)) {
+          // Convert status code to a string
+          let e = Components.Exception("", status);
+          reject(new Error(`Error while loading '${url}' (${e.name})`));
+          return;
+        }
+        try {
+          let text = lazy.NetUtil.readInputStreamToString(
+            inputStream,
+            inputStream.available()
+          );
+
+          // Chrome JSON files include a license comment that we need to
+          // strip off for this to be valid JSON. As a hack, we just
+          // look for the first '[' character, which signals the start
+          // of the JSON content.
+          let index = text.indexOf("[");
+          text = text.slice(index);
+
+          resolve(JSON.parse(text));
+        } catch (e) {
+          reject(e);
+        }
+      }
+    );
+  });
+}
+
+function stripDescriptions(json, stripThis = true) {
+  if (Array.isArray(json)) {
+    for (let i = 0; i < json.length; i++) {
+      if (typeof json[i] === "object" && json[i] !== null) {
+        json[i] = stripDescriptions(json[i]);
+      }
+    }
+    return json;
+  }
+
+  let result = {};
+
+  // Objects are handled much more efficiently, both in terms of memory and
+  // CPU, if they have the same shape as other objects that serve the same
+  // purpose. So, normalize the order of properties to increase the chances
+  // that the majority of schema objects wind up in large shape groups.
+  for (let key of Object.keys(json).sort()) {
+    if (stripThis && key === "description" && typeof json[key] === "string") {
+      continue;
+    }
+
+    if (typeof json[key] === "object" && json[key] !== null) {
+      result[key] = stripDescriptions(json[key], key !== "properties");
+    } else {
+      result[key] = json[key];
+    }
+  }
+
+  return result;
+}
+
+function blobbify(json) {
+  // We don't actually use descriptions at runtime, and they make up about a
+  // third of the size of our structured clone data, so strip them before
+  // blobbifying.
+  json = stripDescriptions(json);
+
+  return new StructuredCloneHolder("Schemas/blobbify", null, json);
+}
+
+async function readJSONAndBlobbify(url) {
+  let json = await readJSON(url);
+
+  return blobbify(json);
+}
+
+/**
+ * Defines a lazy getter for the given property on the given object. Any
+ * security wrappers are waived on the object before the property is
+ * defined, and the getter and setter methods are wrapped for the target
+ * scope.
+ *
+ * The given getter function is guaranteed to be called only once, even
+ * if the target scope retrieves the wrapped getter from the property
+ * descriptor and calls it directly.
+ *
+ * @param {object} object
+ *        The object on which to define the getter.
+ * @param {string | symbol} prop
+ *        The property name for which to define the getter.
+ * @param {Function} getter
+ *        The function to call in order to generate the final property
+ *        value.
+ */
+function exportLazyGetter(object, prop, getter) {
+  object = ChromeUtils.waiveXrays(object);
+
+  let redefine = value => {
+    if (value === undefined) {
+      delete object[prop];
+    } else {
+      Object.defineProperty(object, prop, {
+        enumerable: true,
+        configurable: true,
+        writable: true,
+        value,
+      });
+    }
+
+    getter = null;
+
+    return value;
+  };
+
+  Object.defineProperty(object, prop, {
+    enumerable: true,
+    configurable: true,
+
+    get: Cu.exportFunction(function () {
+      return redefine(getter.call(this));
+    }, object),
+
+    set: Cu.exportFunction(value => {
+      redefine(value);
+    }, object),
+  });
+}
+
+/**
+ * Defines a lazily-instantiated property descriptor on the given
+ * object. Any security wrappers are waived on the object before the
+ * property is defined.
+ *
+ * The given getter function is guaranteed to be called only once, even
+ * if the target scope retrieves the wrapped getter from the property
+ * descriptor and calls it directly.
+ *
+ * @param {object} object
+ *        The object on which to define the getter.
+ * @param {string | symbol} prop
+ *        The property name for which to define the getter.
+ * @param {Function} getter
+ *        The function to call in order to generate the final property
+ *        descriptor object. This will be called, and the property
+ *        descriptor installed on the object, the first time the
+ *        property is written or read. The function may return
+ *        undefined, which will cause the property to be deleted.
+ */
+function exportLazyProperty(object, prop, getter) {
+  object = ChromeUtils.waiveXrays(object);
+
+  let redefine = obj => {
+    let desc = getter.call(obj);
+    getter = null;
+
+    delete object[prop];
+    if (desc) {
+      let defaults = {
+        configurable: true,
+        enumerable: true,
+      };
+
+      if (!desc.set && !desc.get) {
+        defaults.writable = true;
+      }
+
+      Object.defineProperty(object, prop, Object.assign(defaults, desc));
+    }
+  };
+
+  Object.defineProperty(object, prop, {
+    enumerable: true,
+    configurable: true,
+
+    get: Cu.exportFunction(function () {
+      redefine(this);
+      return object[prop];
+    }, object),
+
+    set: Cu.exportFunction(function (value) {
+      redefine(this);
+      object[prop] = value;
+    }, object),
+  });
+}
+
+const POSTPROCESSORS = {
+  convertImageDataToURL(imageData, context) {
+    let document = context.cloneScope.document;
+    let canvas = document.createElementNS(
+      "http://www.w3.org/1999/xhtml",
+      "canvas"
+    );
+    canvas.width = imageData.width;
+    canvas.height = imageData.height;
+    canvas.getContext("2d").putImageData(imageData, 0, 0);
+
+    return canvas.toDataURL("image/png");
+  },
+  webRequestBlockingPermissionRequired(string, context) {
+    if (string === "blocking" && !context.hasPermission("webRequestBlocking")) {
+      throw new context.cloneScope.Error(
+        "Using webRequest.addListener with the " +
+          "blocking option requires the 'webRequestBlocking' permission."
+      );
+    }
+
+    return string;
+  },
+  requireBackgroundServiceWorkerEnabled(value, context) {
+    if (WebExtensionPolicy.backgroundServiceWorkerEnabled) {
+      return value;
+    }
+
+    // Add an error to the manifest validations and throw the
+    // same error.
+    const msg = "background.service_worker is currently disabled";
+    context.logError(context.makeError(msg));
+    throw new Error(msg);
+  },
+
+  manifestVersionCheck(value, context) {
+    if (
+      value == 2 ||
+      (value == 3 &&
+        Services.prefs.getBoolPref("extensions.manifestV3.enabled", false))
+    ) {
+      return value;
+    }
+    const msg = `Unsupported manifest version: ${value}`;
+    context.logError(context.makeError(msg));
+    throw new Error(msg);
+  },
+
+  webAccessibleMatching(value, context) {
+    // Ensure each object has at least one of matches or extension_ids array.
+    for (let obj of value) {
+      if (!obj.matches && !obj.extension_ids) {
+        const msg = `web_accessible_resources requires one of "matches" or "extension_ids"`;
+        context.logError(context.makeError(msg));
+        throw new Error(msg);
+      }
+    }
+    return value;
+  },
+};
+
+// Parses a regular expression, with support for the Python extended
+// syntax that allows setting flags by including the string (?im)
+function parsePattern(pattern) {
+  let flags = "";
+  let match = /^\(\?([im]*)\)(.*)/.exec(pattern);
+  if (match) {
+    [, flags, pattern] = match;
+  }
+  return new RegExp(pattern, flags);
+}
+
+function getValueBaseType(value) {
+  let type = typeof value;
+  switch (type) {
+    case "object":
+      if (value === null) {
+        return "null";
+      }
+      if (Array.isArray(value)) {
+        return "array";
+      }
+      break;
+
+    case "number":
+      if (value % 1 === 0) {
+        return "integer";
+      }
+  }
+  return type;
+}
+
+// Methods of Context that are used by Schemas.normalize. These methods can be
+// overridden at the construction of Context.
+const CONTEXT_FOR_VALIDATION = ["checkLoadURL", "hasPermission", "logError"];
+
+// Methods of Context that are used by Schemas.inject.
+// Callers of Schemas.inject should implement all of these methods.
+const CONTEXT_FOR_INJECTION = [
+  ...CONTEXT_FOR_VALIDATION,
+  "getImplementation",
+  "isPermissionRevokable",
+  "shouldInject",
+];
+
+// If the message is a function, call it and return the result.
+// Otherwise, assume it's a string.
+function forceString(msg) {
+  if (typeof msg === "function") {
+    return msg();
+  }
+  return msg;
+}
+
+/**
+ * A context for schema validation and error reporting. This class is only used
+ * internally within Schemas.
+ */
+class Context {
+  /**
+   * @param {object} params Provides the implementation of this class.
+   * @param {Array<string>} overridableMethods
+   */
+  constructor(params, overridableMethods = CONTEXT_FOR_VALIDATION) {
+    this.params = params;
+
+    if (typeof params.manifestVersion !== "number") {
+      throw new Error(
+        `Unexpected params.manifestVersion value: ${params.manifestVersion}`
+      );
+    }
+
+    this.path = [];
+    this.preprocessors = {
+      localize(value, context) {
+        return value;
+      },
+      ...params.preprocessors,
+    };
+
+    this.postprocessors = POSTPROCESSORS;
+    this.isChromeCompat = params.isChromeCompat ?? false;
+    this.manifestVersion = params.manifestVersion;
+
+    this.currentChoices = new Set();
+    this.choicePathIndex = 0;
+
+    for (let method of overridableMethods) {
+      if (method in params) {
+        this[method] = params[method].bind(params);
+      }
+    }
+  }
+
+  get choicePath() {
+    let path = this.path.slice(this.choicePathIndex);
+    return path.join(".");
+  }
+
+  get cloneScope() {
+    return this.params.cloneScope || undefined;
+  }
+
+  get url() {
+    return this.params.url;
+  }
+
+  get principal() {
+    return (
+      this.params.principal ||
+      Services.scriptSecurityManager.createNullPrincipal({})
+    );
+  }
+
+  /**
+   * Checks whether `url` may be loaded by the extension in this context.
+   *
+   * @param {string} url The URL that the extension wished to load.
+   * @returns {boolean} Whether the context may load `url`.
+   */
+  checkLoadURL(url) {
+    let ssm = Services.scriptSecurityManager;
+    try {
+      ssm.checkLoadURIWithPrincipal(
+        this.principal,
+        Services.io.newURI(url),
+        ssm.DISALLOW_INHERIT_PRINCIPAL
+      );
+    } catch (e) {
+      return false;
+    }
+    return true;
+  }
+
+  /**
+   * Checks whether this context has the given permission.
+   *
+   * @param {string} permission
+   *        The name of the permission to check.
+   *
+   * @returns {boolean} True if the context has the given permission.
+   */
+  hasPermission(permission) {
+    return false;
+  }
+
+  /**
+   * Checks whether the given permission can be dynamically revoked or
+   * granted.
+   *
+   * @param {string} permission
+   *        The name of the permission to check.
+   *
+   * @returns {boolean} True if the given permission is revokable.
+   */
+  isPermissionRevokable(permission) {
+    return false;
+  }
+
+  /**
+   * Returns an error result object with the given message, for return
+   * by Type normalization functions.
+   *
+   * If the context has a `currentTarget` value, this is prepended to
+   * the message to indicate the location of the error.
+   *
+   * @param {string | Function} errorMessage
+   *        The error message which will be displayed when this is the
+   *        only possible matching schema. If a function is passed, it
+   *        will be evaluated when the error string is first needed, and
+   *        must return a string.
+   * @param {string | Function} choicesMessage
+   *        The message describing the valid what constitutes a valid
+   *        value for this schema, which will be displayed when multiple
+   *        schema choices are available and none match.
+   *
+   *        A caller may pass `null` to prevent a choice from being
+   *        added, but this should *only* be done from code processing a
+   *        choices type.
+   * @param {boolean} [warning = false]
+   *        If true, make message prefixed `Warning`. If false, make message
+   *        prefixed `Error`
+   * @returns {object}
+   */
+  error(errorMessage, choicesMessage = undefined, warning = false) {
+    if (choicesMessage !== null) {
+      let { choicePath } = this;
+      if (choicePath) {
+        choicesMessage = `.${choicePath} must ${choicesMessage}`;
+      }
+
+      this.currentChoices.add(choicesMessage);
+    }
+
+    if (this.currentTarget) {
+      let { currentTarget } = this;
+      return {
+        error: () =>
+          `${
+            warning ? "Warning" : "Error"
+          } processing ${currentTarget}: ${forceString(errorMessage)}`,
+      };
+    }
+    return { error: errorMessage };
+  }
+
+  /**
+   * Creates an `Error` object belonging to the current unprivileged
+   * scope. If there is no unprivileged scope associated with this
+   * context, the message is returned as a string.
+   *
+   * If the context has a `currentTarget` value, this is prepended to
+   * the message, in the same way as for the `error` method.
+   *
+   * @param {string} message
+   * @param {object} [options]
+   * @param {boolean} [options.warning = false]
+   * @returns {Error}
+   */
+  makeError(message, { warning = false } = {}) {
+    let error = forceString(this.error(message, null, warning).error);
+    if (this.cloneScope) {
+      return new this.cloneScope.Error(error);
+    }
+    return error;
+  }
+
+  /**
+   * Logs the given error to the console. May be overridden to enable
+   * custom logging.
+   *
+   * @param {Error|string} error
+   */
+  logError(error) {
+    if (this.cloneScope) {
+      Cu.reportError(
+        // Error objects logged using Cu.reportError are not associated
+        // to the related innerWindowID. This results in a leaked docshell
+        // since consoleService cannot release the error object when the
+        // extension global is destroyed.
+        typeof error == "string" ? error : String(error),
+        // Report the error with the appropriate stack trace when the
+        // is related to an actual extension global (instead of being
+        // related to a manifest validation).
+        this.principal && ChromeUtils.getCallerLocation(this.principal)
+      );
+    } else {
+      Cu.reportError(error);
+    }
+  }
+
+  /**
+   * Logs a warning. An error might be thrown when we treat warnings as errors.
+   *
+   * @param {string} warningMessage
+   */
+  logWarning(warningMessage) {
+    let error = this.makeError(warningMessage, { warning: true });
+    this.logError(error);
+
+    if (lazy.treatWarningsAsErrors) {
+      // This pref is false by default, and true by default in tests to
+      // discourage the use of deprecated APIs in our unit tests.
+      // If a warning is an expected part of a test, temporarily set the pref
+      // to false, e.g. with the ExtensionTestUtils.failOnSchemaWarnings helper.
+      Services.console.logStringMessage(
+        "Treating warning as error because the preference " +
+          "extensions.webextensions.warnings-as-errors is set to true"
+      );
+      if (typeof error === "string") {
+        error = new Error(error);
+      }
+      throw error;
+    }
+  }
+
+  /**
+   * Returns the name of the value currently being normalized. For a
+   * nested object, this is usually approximately equivalent to the
+   * JavaScript property accessor for that property. Given:
+   *
+   *   { foo: { bar: [{ baz: x }] } }
+   *
+   * When processing the value for `x`, the currentTarget is
+   * 'foo.bar.0.baz'
+   */
+  get currentTarget() {
+    return this.path.join(".");
+  }
+
+  /**
+   * Executes the given callback, and returns an array of choice strings
+   * passed to {@see #error} during its execution.
+   *
+   * @param {Function} callback
+   * @returns {object}
+   *          An object with a `result` property containing the return
+   *          value of the callback, and a `choice` property containing
+   *          an array of choices.
+   */
+  withChoices(callback) {
+    let { currentChoices, choicePathIndex } = this;
+
+    let choices = new Set();
+    this.currentChoices = choices;
+    this.choicePathIndex = this.path.length;
+
+    try {
+      let result = callback();
+
+      return { result, choices };
+    } finally {
+      this.currentChoices = currentChoices;
+      this.choicePathIndex = choicePathIndex;
+
+      if (choices.size == 1) {
+        for (let choice of choices) {
+          currentChoices.add(choice);
+        }
+      } else if (choices.size) {
+        this.error(null, () => {
+          let array = Array.from(choices, forceString);
+          let n = array.length - 1;
+          array[n] = `or ${array[n]}`;
+
+          return `must either [${array.join(", ")}]`;
+        });
+      }
+    }
+  }
+
+  /**
+   * Appends the given component to the `currentTarget` path to indicate
+   * that it is being processed, calls the given callback function, and
+   * then restores the original path.
+   *
+   * This is used to identify the path of the property being processed
+   * when reporting type errors.
+   *
+   * @param {string} component
+   * @param {Function} callback
+   * @returns {*}
+   */
+  withPath(component, callback) {
+    this.path.push(component);
+    try {
+      return callback();
+    } finally {
+      this.path.pop();
+    }
+  }
+
+  matchManifestVersion(entry) {
+    let { manifestVersion } = this;
+    return (
+      manifestVersion >= entry.min_manifest_version &&
+      manifestVersion <= entry.max_manifest_version
+    );
+  }
+}
+
+/**
+ * Represents a schema entry to be injected into an object. Handles the
+ * injection, revocation, and permissions of said entry.
+ *
+ * @param {InjectionContext} context
+ *        The injection context for the entry.
+ * @param {Entry} entry
+ *        The entry to inject.
+ * @param {object} parentObject
+ *        The object into which to inject this entry.
+ * @param {string} name
+ *        The property name at which to inject this entry.
+ * @param {Array<string>} path
+ *        The full path from the root entry to this entry.
+ * @param {Entry} parentEntry
+ *        The parent entry for the injected entry.
+ */
+class InjectionEntry {
+  constructor(context, entry, parentObj, name, path, parentEntry) {
+    this.context = context;
+    this.entry = entry;
+    this.parentObj = parentObj;
+    this.name = name;
+    this.path = path;
+    this.parentEntry = parentEntry;
+
+    this.injected = null;
+    this.lazyInjected = null;
+  }
+
+  /**
+   * @property {Array<string>} allowedContexts
+   *        The list of allowed contexts into which the entry may be
+   *        injected.
+   */
+  get allowedContexts() {
+    let { allowedContexts } = this.entry;
+    if (allowedContexts.length) {
+      return allowedContexts;
+    }
+    return this.parentEntry.defaultContexts;
+  }
+
+  /**
+   * @property {boolean} isRevokable
+   *        Returns true if this entry may be dynamically injected or
+   *        revoked based on its permissions.
+   */
+  get isRevokable() {
+    return (
+      this.entry.permissions &&
+      this.entry.permissions.some(perm =>
+        this.context.isPermissionRevokable(perm)
+      )
+    );
+  }
+
+  /**
+   * @property {boolean} hasPermission
+   *        Returns true if the injection context currently has the
+   *        appropriate permissions to access this entry.
+   */
+  get hasPermission() {
+    return (
+      !this.entry.permissions ||
+      this.entry.permissions.some(perm => this.context.hasPermission(perm))
+    );
+  }
+
+  /**
+   * @property {boolean} shouldInject
+   *        Returns true if this entry should be injected in the given
+   *        context, without respect to permissions.
+   */
+  get shouldInject() {
+    return (
+      this.context.matchManifestVersion(this.entry) &&
+      this.context.shouldInject(
+        this.path.join("."),
+        this.name,
+        this.allowedContexts
+      )
+    );
+  }
+
+  /**
+   * Revokes this entry, removing its property from its parent object,
+   * and invalidating its wrappers.
+   */
+  revoke() {
+    if (this.lazyInjected) {
+      this.lazyInjected = false;
+    } else if (this.injected) {
+      if (this.injected.revoke) {
+        this.injected.revoke();
+      }
+
+      try {
+        let unwrapped = ChromeUtils.waiveXrays(this.parentObj);
+        delete unwrapped[this.name];
+      } catch (e) {
+        Cu.reportError(e);
+      }
+
+      let { value } = this.injected.descriptor;
+      if (value) {
+        this.context.revokeChildren(value);
+      }
+
+      this.injected = null;
+    }
+  }
+
+  /**
+   * Returns a property descriptor object for this entry, if it should
+   * be injected, or undefined if it should not.
+   *
+   * @returns {object?}
+   *        A property descriptor object, or undefined if the property
+   *        should be removed.
+   */
+  getDescriptor() {
+    this.lazyInjected = false;
+
+    if (this.injected) {
+      let path = [...this.path, this.name];
+      throw new Error(
+        `Attempting to re-inject already injected entry: ${path.join(".")}`
+      );
+    }
+
+    if (!this.shouldInject) {
+      return;
+    }
+
+    if (this.isRevokable) {
+      this.context.pendingEntries.add(this);
+    }
+
+    if (!this.hasPermission) {
+      return;
+    }
+
+    this.injected = this.entry.getDescriptor(this.path, this.context);
+    if (!this.injected) {
+      return undefined;
+    }
+
+    return this.injected.descriptor;
+  }
+
+  /**
+   * Injects a lazy property descriptor into the parent object which
+   * checks permissions and eligibility for injection the first time it
+   * is accessed.
+   */
+  lazyInject() {
+    if (this.lazyInjected || this.injected) {
+      let path = [...this.path, this.name];
+      throw new Error(
+        `Attempting to re-lazy-inject already injected entry: ${path.join(".")}`
+      );
+    }
+
+    this.lazyInjected = true;
+    exportLazyProperty(this.parentObj, this.name, () => {
+      if (this.lazyInjected) {
+        return this.getDescriptor();
+      }
+    });
+  }
+
+  /**
+   * Injects or revokes this entry if its current state does not match
+   * the context's current permissions.
+   */
+  permissionsChanged() {
+    if (this.injected) {
+      this.maybeRevoke();
+    } else {
+      this.maybeInject();
+    }
+  }
+
+  maybeInject() {
+    if (!this.injected && !this.lazyInjected) {
+      this.lazyInject();
+    }
+  }
+
+  maybeRevoke() {
+    if (this.injected && !this.hasPermission) {
+      this.revoke();
+    }
+  }
+}
+
+/**
+ * Holds methods that run the actual implementation of the extension APIs. These
+ * methods are only called if the extension API invocation matches the signature
+ * as defined in the schema. Otherwise an error is reported to the context.
+ */
+class InjectionContext extends Context {
+  constructor(params, schemaRoot) {
+    super(params, CONTEXT_FOR_INJECTION);
+
+    this.schemaRoot = schemaRoot;
+
+    this.pendingEntries = new Set();
+    this.children = new DefaultWeakMap(() => new Map());
+
+    this.injectedRoots = new Set();
+
+    if (params.setPermissionsChangedCallback) {
+      params.setPermissionsChangedCallback(this.permissionsChanged.bind(this));
+    }
+  }
+
+  /**
+   * Check whether the API should be injected.
+   *
+   * @abstract
+   * @param {string} namespace The namespace of the API. This may contain dots,
+   *     e.g. in the case of "devtools.inspectedWindow".
+   * @param {string?} name The name of the property in the namespace.
+   *     `null` if we are checking whether the namespace should be injected.
+   * @param {Array<string>} allowedContexts A list of additional contexts in
+   *      which this API should be available. May include any of:
+   *         "main" - The main chrome browser process.
+   *         "addon" - An addon process.
+   *         "content" - A content process.
+   * @returns {boolean} Whether the API should be injected.
+   */
+  shouldInject(namespace, name, allowedContexts) {
+    throw new Error("Not implemented");
+  }
+
+  /**
+   * Generate the implementation for `namespace`.`name`.
+   *
+   * @abstract
+   * @param {string} namespace The full path to the namespace of the API, minus
+   *     the name of the method or property. E.g. "storage.local".
+   * @param {string} name The name of the method, property or event.
+   * @returns {SchemaAPIInterface} The implementation of the API.
+   */
+  getImplementation(namespace, name) {
+    throw new Error("Not implemented");
+  }
+
+  /**
+   * Updates all injection entries which may need to be updated after a
+   * permission change, revoking or re-injecting them as necessary.
+   */
+  permissionsChanged() {
+    for (let entry of this.pendingEntries) {
+      try {
+        entry.permissionsChanged();
+      } catch (e) {
+        Cu.reportError(e);
+      }
+    }
+  }
+
+  /**
+   * Recursively revokes all child injection entries of the given
+   * object.
+   *
+   * @param {object} object
+   *        The object for which to invoke children.
+   */
+  revokeChildren(object) {
+    if (!this.children.has(object)) {
+      return;
+    }
+
+    let children = this.children.get(object);
+    for (let [name, entry] of children.entries()) {
+      try {
+        entry.revoke();
+      } catch (e) {
+        Cu.reportError(e);
+      }
+      children.delete(name);
+
+      // When we revoke children for an object, we consider that object
+      // dead. If the entry is ever reified again, a new object is
+      // created, with new child entries.
+      this.pendingEntries.delete(entry);
+    }
+    this.children.delete(object);
+  }
+
+  _getInjectionEntry(entry, dest, name, path, parentEntry) {
+    let injection = new InjectionEntry(
+      this,
+      entry,
+      dest,
+      name,
+      path,
+      parentEntry
+    );
+
+    this.children.get(dest).set(name, injection);
+
+    return injection;
+  }
+
+  /**
+   * Returns the property descriptor for the given entry.
+   *
+   * @param {Entry} entry
+   *        The entry instance to return a descriptor for.
+   * @param {object} dest
+   *        The object into which this entry is being injected.
+   * @param {string} name
+   *        The property name on the destination object where the entry
+   *        will be injected.
+   * @param {Array<string>} path
+   *        The full path from the root injection object to this entry.
+   * @param {Partial<Entry>} parentEntry
+   *        The parent entry for this entry.
+   *
+   * @returns {object?}
+   *        A property descriptor object, or null if the entry should
+   *        not be injected.
+   */
+  getDescriptor(entry, dest, name, path, parentEntry) {
+    let injection = this._getInjectionEntry(
+      entry,
+      dest,
+      name,
+      path,
+      parentEntry
+    );
+
+    return injection.getDescriptor();
+  }
+
+  /**
+   * Lazily injects the given entry into the given object.
+   *
+   * @param {Entry} entry
+   *        The entry instance to lazily inject.
+   * @param {object} dest
+   *        The object into which to inject this entry.
+   * @param {string} name
+   *        The property name at which to inject the entry.
+   * @param {Array<string>} path
+   *        The full path from the root injection object to this entry.
+   * @param {Entry} parentEntry
+   *        The parent entry for this entry.
+   */
+  injectInto(entry, dest, name, path, parentEntry) {
+    let injection = this._getInjectionEntry(
+      entry,
+      dest,
+      name,
+      path,
+      parentEntry
+    );
+
+    injection.lazyInject();
+  }
+}
+
+/**
+ * The methods in this singleton represent the "format" specifier for
+ * JSON Schema string types.
+ *
+ * Each method either returns a normalized version of the original
+ * value, or throws an error if the value is not valid for the given
+ * format.
+ */
+const FORMATS = {
+  hostname(string, context) {
+    // TODO bug 1797376: Despite the name, this format is NOT a "hostname",
+    // but hostname + port and may fail with IPv6. Use canonicalDomain instead.
+    let valid = true;
+
+    try {
+      valid = new URL(`http://${string}`).host === string;
+    } catch (e) {
+      valid = false;
+    }
+
+    if (!valid) {
+      throw new Error(`Invalid hostname ${string}`);
+    }
+
+    return string;
+  },
+
+  canonicalDomain(string, context) {
+    let valid;
+
+    try {
+      valid = new URL(`http://${string}`).hostname === string;
+    } catch (e) {
+      valid = false;
+    }
+
+    if (!valid) {
+      // Require the input to be a canonical domain.
+      // Rejects obvious non-domains such as URLs,
+      // but also catches non-IDN (punycode) domains.
+      throw new Error(`Invalid domain ${string}`);
+    }
+
+    return string;
+  },
+
+  url(string, context) {
+    let url = new URL(string).href;
+
+    if (!context.checkLoadURL(url)) {
+      throw new Error(`Access denied for URL ${url}`);
+    }
+    return url;
+  },
+
+  origin(string, context) {
+    let url;
+    try {
+      url = new URL(string);
+    } catch (e) {
+      throw new Error(`Invalid origin: ${string}`);
+    }
+    if (!/^https?:/.test(url.protocol)) {
+      throw new Error(`Invalid origin must be http or https for URL ${string}`);
+    }
+    // url.origin is punycode so a direct check against string wont work.
+    // url.href appends a slash even if not in the original string, we we
+    // additionally check that string does not end in slash.
+    if (string.endsWith("/") || url.href != new URL(url.origin).href) {
+      throw new Error(
+        `Invalid origin for URL ${string}, replace with origin ${url.origin}`
+      );
+    }
+    if (!context.checkLoadURL(url.origin)) {
+      throw new Error(`Access denied for URL ${url}`);
+    }
+    return url.origin;
+  },
+
+  relativeUrl(string, context) {
+    if (!context.url) {
+      // If there's no context URL, return relative URLs unresolved, and
+      // skip security checks for them.
+      try {
+        new URL(string);
+      } catch (e) {
+        return string;
+      }
+    }
+
+    let url = new URL(string, context.url).href;
+
+    if (!context.checkLoadURL(url)) {
+      throw new Error(`Access denied for URL ${url}`);
+    }
+    return url;
+  },
+
+  strictRelativeUrl(string, context) {
+    void FORMATS.unresolvedRelativeUrl(string, context);
+    return FORMATS.relativeUrl(string, context);
+  },
+
+  unresolvedRelativeUrl(string, context) {
+    if (!string.startsWith("//")) {
+      try {
+        new URL(string);
+      } catch (e) {
+        return string;
+      }
+    }
+
+    throw new SyntaxError(
+      `String ${JSON.stringify(string)} must be a relative URL`
+    );
+  },
+
+  homepageUrl(string, context) {
+    // Pipes are used for separating homepages, but we only allow extensions to
+    // set a single homepage. Encoding any pipes makes it one URL.
+    return FORMATS.relativeUrl(
+      string.replace(new RegExp("\\|", "g"), "%7C"),
+      context
+    );
+  },
+
+  imageDataOrStrictRelativeUrl(string, context) {
+    // Do not accept a string which resolves as an absolute URL, or any
+    // protocol-relative URL, except PNG or JPG data URLs
+    if (
+      !string.startsWith("data:image/png;base64,") &&
+      !string.startsWith("data:image/jpeg;base64,")
+    ) {
+      try {
+        return FORMATS.strictRelativeUrl(string, context);
+      } catch (e) {
+        throw new SyntaxError(
+          `String ${JSON.stringify(
+            string
+          )} must be a relative or PNG or JPG data:image URL`
+        );
+      }
+    }
+    return string;
+  },
+
+  contentSecurityPolicy(string, context) {
+    // Manifest V3 extension_pages allows WASM.  When sandbox is
+    // implemented, or any other V3 or later directive, the flags
+    // logic will need to be updated.
+    let flags =
+      context.manifestVersion < 3
+        ? Ci.nsIAddonContentPolicy.CSP_ALLOW_ANY
+        : Ci.nsIAddonContentPolicy.CSP_ALLOW_WASM;
+    let error = lazy.contentPolicyService.validateAddonCSP(string, flags);
+    if (error != null) {
+      // The CSP validation error is not reported as part of the "choices" error message,
+      // we log the CSP validation error explicitly here to make it easier for the addon developers
+      // to see and fix the extension CSP.
+      context.logError(`Error processing ${context.currentTarget}: ${error}`);
+      return null;
+    }
+    return string;
+  },
+
+  date(string, context) {
+    // A valid ISO 8601 timestamp.
+    const PATTERN =
+      /^\d{4}-\d{2}-\d{2}(T\d{2}:\d{2}:\d{2}(\.\d{3})?(Z|([-+]\d{2}:?\d{2})))?$/;
+    if (!PATTERN.test(string)) {
+      throw new Error(`Invalid date string ${string}`);
+    }
+    // Our pattern just checks the format, we could still have invalid
+    // values (e.g., month=99 or month=02 and day=31).  Let the Date
+    // constructor do the dirty work of validating.
+    if (isNaN(Date.parse(string))) {
+      throw new Error(`Invalid date string ${string}`);
+    }
+    return string;
+  },
+
+  manifestShortcutKey(string, context) {
+    if (lazy.ShortcutUtils.validate(string) == lazy.ShortcutUtils.IS_VALID) {
+      return string;
+    }
+    let errorMessage =
+      `Value "${string}" must consist of ` +
+      `either a combination of one or two modifiers, including ` +
+      `a mandatory primary modifier and a key, separated by '+', ` +
+      `or a media key. For details see: ` +
+      `https://developer.mozilla.org/en-US/Add-ons/WebExtensions/manifest.json/commands#Key_combinations`;
+    throw new Error(errorMessage);
+  },
+
+  manifestShortcutKeyOrEmpty(string, context) {
+    return string === "" ? "" : FORMATS.manifestShortcutKey(string, context);
+  },
+
+  versionString(string, context) {
+    const parts = string.split(".");
+
+    if (
+      // We accept up to 4 numbers.
+      parts.length > 4 ||
+      // Non-zero values cannot start with 0 and we allow numbers up to 9 digits.
+      parts.some(part => !/^(0|[1-9][0-9]{0,8})$/.test(part))
+    ) {
+      context.logWarning(
+        `version must be a version string consisting of at most 4 integers ` +
+          `of at most 9 digits without leading zeros, and separated with dots`
+      );
+    }
+
+    // The idea is to only emit a warning when the version string does not
+    // match the simple format we want to encourage developers to use. Given
+    // the version is required, we always accept the value as is.
+    return string;
+  },
+};
+
+// Schema files contain namespaces, and each namespace contains types,
+// properties, functions, and events. An Entry is a base class for
+// types, properties, functions, and events.
+class Entry {
+  constructor(schema = {}) {
+    /**
+     * If set to any value which evaluates as true, this entry is
+     * deprecated, and any access to it will result in a deprecation
+     * warning being logged to the browser console.
+     *
+     * If the value is a string, it will be appended to the deprecation
+     * message. If it contains the substring "${value}", it will be
+     * replaced with a string representation of the value being
+     * processed.
+     *
+     * If the value is any other truthy value, a generic deprecation
+     * message will be emitted.
+     */
+    this.deprecated = false;
+    if ("deprecated" in schema) {
+      this.deprecated = schema.deprecated;
+    }
+
+    /**
+     * @property {string} [preprocessor]
+     * If set to a string value, and a preprocessor of the same is
+     * defined in the validation context, it will be applied to this
+     * value prior to any normalization.
+     */
+    this.preprocessor = schema.preprocess || null;
+
+    /**
+     * @property {string} [postprocessor]
+     * If set to a string value, and a postprocessor of the same is
+     * defined in the validation context, it will be applied to this
+     * value after any normalization.
+     */
+    this.postprocessor = schema.postprocess || null;
+
+    /**
+     * @property {Array<string>} allowedContexts A list of allowed contexts
+     * to consider before generating the API.
+     * These are not parsed by the schema, but passed to `shouldInject`.
+     */
+    this.allowedContexts = schema.allowedContexts || [];
+
+    this.min_manifest_version =
+      schema.min_manifest_version ?? MIN_MANIFEST_VERSION;
+    this.max_manifest_version =
+      schema.max_manifest_version ?? MAX_MANIFEST_VERSION;
+  }
+
+  /**
+   * Preprocess the given value with the preprocessor declared in
+   * `preprocessor`.
+   *
+   * @param {*} value
+   * @param {Context} context
+   * @returns {*}
+   */
+  preprocess(value, context) {
+    if (this.preprocessor) {
+      return context.preprocessors[this.preprocessor](value, context);
+    }
+    return value;
+  }
+
+  /**
+   * Postprocess the given result with the postprocessor declared in
+   * `postprocessor`.
+   *
+   * @param {object} result
+   * @param {Context} context
+   * @returns {object}
+   */
+  postprocess(result, context) {
+    if (result.error || !this.postprocessor) {
+      return result;
+    }
+
+    let value = context.postprocessors[this.postprocessor](
+      result.value,
+      context
+    );
+    return { value };
+  }
+
+  /**
+   * Logs a deprecation warning for this entry, based on the value of
+   * its `deprecated` property.
+   *
+   * @param {Context} context
+   * @param {any} [value]
+   */
+  logDeprecation(context, value = null) {
+    let message = "This property is deprecated";
+    if (typeof this.deprecated == "string") {
+      message = this.deprecated;
+      if (message.includes("${value}")) {
+        try {
+          value = JSON.stringify(value);
+        } catch (e) {
+          value = String(value);
+        }
+        message = message.replace(/\$\{value\}/g, () => value);
+      }
+    }
+
+    context.logWarning(message);
+  }
+
+  /**
+   * Checks whether the entry is deprecated and, if so, logs a
+   * deprecation message.
+   *
+   * @param {Context} context
+   * @param {any} [value]
+   */
+  checkDeprecated(context, value = null) {
+    if (this.deprecated) {
+      this.logDeprecation(context, value);
+    }
+  }
+
+  /**
+   * Returns an object containing property descriptor for use when
+   * injecting this entry into an API object.
+   *
+   * @param {Array<string>} path The API path, e.g. `["storage", "local"]`.
+   * @param {InjectionContext} context
+   *
+   * @returns {object?}
+   *        An object containing a `descriptor` property, specifying the
+   *        entry's property descriptor, and an optional `revoke`
+   *        method, to be called when the entry is being revoked.
+   */
+  getDescriptor(path, context) {
+    return undefined;
+  }
+}
+
+// Corresponds either to a type declared in the "types" section of the
+// schema or else to any type object used throughout the schema.
+class Type extends Entry {
+  /**
+   * @property {Array<string>} EXTRA_PROPERTIES
+   *        An array of extra properties which may be present for
+   *        schemas of this type.
+   */
+  static get EXTRA_PROPERTIES() {
+    return [
+      "description",
+      "deprecated",
+      "preprocess",
+      "postprocess",
+      "privileged",
+      "allowedContexts",
+      "min_manifest_version",
+      "max_manifest_version",
+    ];
+  }
+
+  /**
+   * Parses the given schema object and returns an instance of this
+   * class which corresponds to its properties.
+   *
+   * @param {SchemaRoot} root
+   *        The root schema for this type.
+   * @param {object} schema
+   *        A JSON schema object which corresponds to a definition of
+   *        this type.
+   * @param {Array<string>} path
+   *        The path to this schema object from the root schema,
+   *        corresponding to the property names and array indices
+   *        traversed during parsing in order to arrive at this schema
+   *        object.
+   * @param {Array<string>} [extraProperties]
+   *        An array of extra property names which are valid for this
+   *        schema in the current context.
+   * @returns {Type}
+   *        An instance of this type which corresponds to the given
+   *        schema object.
+   * @static
+   */
+  static parseSchema(root, schema, path, extraProperties = []) {
+    this.checkSchemaProperties(schema, path, extraProperties);
+
+    return new this(schema);
+  }
+
+  /**
+   * Checks that all of the properties present in the given schema
+   * object are valid properties for this type, and throws if invalid.
+   *
+   * @param {object} schema
+   *        A JSON schema object.
+   * @param {Array<string>} path
+   *        The path to this schema object from the root schema,
+   *        corresponding to the property names and array indices
+   *        traversed during parsing in order to arrive at this schema
+   *        object.
+   * @param {Iterable<string>} [extra]
+   *        An array of extra property names which are valid for this
+   *        schema in the current context.
+   * @throws {Error}
+   *        An error describing the first invalid property found in the
+   *        schema object.
+   */
+  static checkSchemaProperties(schema, path, extra = []) {
+    if (DEBUG) {
+      let allowedSet = new Set([...this.EXTRA_PROPERTIES, ...extra]);
+
+      for (let prop of Object.keys(schema)) {
+        if (!allowedSet.has(prop)) {
+          throw new Error(
+            `Internal error: Namespace ${path.join(".")} has ` +
+              `invalid type property "${prop}" ` +
+              `in type "${schema.id || JSON.stringify(schema)}"`
+          );
+        }
+      }
+    }
+  }
+
+  // Takes a value, checks that it has the correct type, and returns a
+  // "normalized" version of the value. The normalized version will
+  // include "nulls" in place of omitted optional properties. The
+  // result of this function is either {error: "Some type error"} or
+  // {value: <normalized-value>}.
+  normalize(value, context) {
+    return context.error("invalid type");
+  }
+
+  // Unlike normalize, this function does a shallow check to see if
+  // |baseType| (one of the possible getValueBaseType results) is
+  // valid for this type. It returns true or false. It's used to fill
+  // in optional arguments to functions before actually type checking
+
+  checkBaseType(baseType) {
+    return false;
+  }
+
+  // Helper method that simply relies on checkBaseType to implement
+  // normalize. Subclasses can choose to use it or not.
+  normalizeBase(type, value, context) {
+    if (this.checkBaseType(getValueBaseType(value))) {
+      this.checkDeprecated(context, value);
+      return { value: this.preprocess(value, context) };
+    }
+
+    let choice;
+    if ("aeiou".includes(type[0])) {
+      choice = `be an ${type} value`;
+    } else {
+      choice = `be a ${type} value`;
+    }
+
+    return context.error(
+      () => `Expected ${type} instead of ${JSON.stringify(value)}`,
+      choice
+    );
+  }
+}
+
+// Type that allows any value.
+class AnyType extends Type {
+  normalize(value, context) {
+    this.checkDeprecated(context, value);
+    return this.postprocess({ value }, context);
+  }
+
+  checkBaseType(baseType) {
+    return true;
+  }
+}
+
+// An untagged union type.
+class ChoiceType extends Type {
+  static get EXTRA_PROPERTIES() {
+    return ["choices", ...super.EXTRA_PROPERTIES];
+  }
+
+  /** @type {(root, schema, path, extraProperties?: Iterable) => ChoiceType} */
+  static parseSchema(root, schema, path, extraProperties = []) {
+    this.checkSchemaProperties(schema, path, extraProperties);
+
+    let choices = schema.choices.map(t => root.parseSchema(t, path));
+    return new this(schema, choices);
+  }
+
+  constructor(schema, choices) {
+    super(schema);
+    this.choices = choices;
+  }
+
+  extend(type) {
+    this.choices.push(...type.choices);
+
+    return this;
+  }
+
+  normalize(value, context) {
+    this.checkDeprecated(context, value);
+
+    let error;
+    let { choices, result } = context.withChoices(() => {
+      for (let choice of this.choices) {
+        // Ignore a possible choice if it is not supported by
+        // the manifest version we are normalizing.
+        if (!context.matchManifestVersion(choice)) {
+          continue;
+        }
+
+        let r = choice.normalize(value, context);
+        if (!r.error) {
+          return r;
+        }
+
+        error = r;
+      }
+    });
+
+    if (result) {
+      return result;
+    }
+    if (choices.size <= 1) {
+      return error;
+    }
+
+    choices = Array.from(choices, forceString);
+    let n = choices.length - 1;
+    choices[n] = `or ${choices[n]}`;
+
+    let message;
+    if (typeof value === "object") {
+      message = () => `Value must either: ${choices.join(", ")}`;
+    } else {
+      message = () =>
+        `Value ${JSON.stringify(value)} must either: ${choices.join(", ")}`;
+    }
+
+    return context.error(message, null);
+  }
+
+  checkBaseType(baseType) {
+    return this.choices.some(t => t.checkBaseType(baseType));
+  }
+
+  getDescriptor(path, context) {
+    // In StringType.getDescriptor, unlike any other Type, a descriptor is returned if
+    // it is an enumeration.  Since we need versioned choices in some cases, here we
+    // build a list of valid enumerations that will work for a given manifest version.
+    if (
+      !this.choices.length ||
+      !this.choices.every(t => t.checkBaseType("string") && t.enumeration)
+    ) {
+      return;
+    }
+
+    let obj = Cu.createObjectIn(context.cloneScope);
+    let descriptor = { value: obj };
+    for (let choice of this.choices) {
+      // Ignore a possible choice if it is not supported by
+      // the manifest version we are normalizing.
+      if (!context.matchManifestVersion(choice)) {
+        continue;
+      }
+      let d = choice.getDescriptor(path, context);
+      if (d) {
+        Object.assign(obj, d.descriptor.value);
+      }
+    }
+
+    return { descriptor };
+  }
+}
+
+// This is a reference to another type--essentially a typedef.
+class RefType extends Type {
+  static get EXTRA_PROPERTIES() {
+    return ["$ref", ...super.EXTRA_PROPERTIES];
+  }
+
+  /** @type {(root, schema, path, extraProperties?: Iterable) => RefType} */
+  static parseSchema(root, schema, path, extraProperties = []) {
+    this.checkSchemaProperties(schema, path, extraProperties);
+
+    let ref = schema.$ref;
+    let ns = path.join(".");
+    if (ref.includes(".")) {
+      [, ns, ref] = /^(.*)\.(.*?)$/.exec(ref);
+    }
+    return new this(root, schema, ns, ref);
+  }
+
+  // For a reference to a type named T declared in namespace NS,
+  // namespaceName will be NS and reference will be T.
+  constructor(root, schema, namespaceName, reference) {
+    super(schema);
+    this.root = root;
+    this.namespaceName = namespaceName;
+    this.reference = reference;
+  }
+
+  get targetType() {
+    let ns = this.root.getNamespace(this.namespaceName);
+    let type = ns.get(this.reference);
+    if (!type) {
+      throw new Error(`Internal error: Type ${this.reference} not found`);
+    }
+    return type;
+  }
+
+  normalize(value, context) {
+    this.checkDeprecated(context, value);
+    return this.targetType.normalize(value, context);
+  }
+
+  checkBaseType(baseType) {
+    return this.targetType.checkBaseType(baseType);
+  }
+}
+
+class StringType extends Type {
+  static get EXTRA_PROPERTIES() {
+    return [
+      "enum",
+      "minLength",
+      "maxLength",
+      "pattern",
+      "format",
+      ...super.EXTRA_PROPERTIES,
+    ];
+  }
+
+  static parseSchema(root, schema, path, extraProperties = []) {
+    this.checkSchemaProperties(schema, path, extraProperties);
+
+    let enumeration = schema.enum || null;
+    if (enumeration) {
+      // The "enum" property is either a list of strings that are
+      // valid values or else a list of {name, description} objects,
+      // where the .name values are the valid values.
+      enumeration = enumeration.map(e => {
+        if (typeof e == "object") {
+          return e.name;
+        }
+        return e;
+      });
+    }
+
+    let pattern = null;
+    if (schema.pattern) {
+      try {
+        pattern = parsePattern(schema.pattern);
+      } catch (e) {
+        throw new Error(
+          `Internal error: Invalid pattern ${JSON.stringify(schema.pattern)}`
+        );
+      }
+    }
+
+    let format = null;
+    if (schema.format) {
+      if (!(schema.format in FORMATS)) {
+        throw new Error(
+          `Internal error: Invalid string format ${schema.format}`
+        );
+      }
+      format = FORMATS[schema.format];
+    }
+    return new this(
+      schema,
+      schema.id || undefined,
+      enumeration,
+      schema.minLength || 0,
+      schema.maxLength || Infinity,
+      pattern,
+      format
+    );
+  }
+
+  constructor(
+    schema,
+    name,
+    enumeration,
+    minLength,
+    maxLength,
+    pattern,
+    format
+  ) {
+    super(schema);
+    this.name = name;
+    this.enumeration = enumeration;
+    this.minLength = minLength;
+    this.maxLength = maxLength;
+    this.pattern = pattern;
+    this.format = format;
+  }
+
+  normalize(value, context) {
+    let r = this.normalizeBase("string", value, context);
+    if (r.error) {
+      return r;
+    }
+    value = r.value;
+
+    if (this.enumeration) {
+      if (this.enumeration.includes(value)) {
+        return this.postprocess({ value }, context);
+      }
+
+      let choices = this.enumeration.map(JSON.stringify).join(", ");
+
+      return context.error(
+        () => `Invalid enumeration value ${JSON.stringify(value)}`,
+        `be one of [${choices}]`
+      );
+    }
+
+    if (value.length < this.minLength) {
+      return context.error(
+        () =>
+          `String ${JSON.stringify(value)} is too short (must be ${
+            this.minLength
+          })`,
+        `be longer than ${this.minLength}`
+      );
+    }
+    if (value.length > this.maxLength) {
+      return context.error(
+        () =>
+          `String ${JSON.stringify(value)} is too long (must be ${
+            this.maxLength
+          })`,
+        `be shorter than ${this.maxLength}`
+      );
+    }
+
+    if (this.pattern && !this.pattern.test(value)) {
+      return context.error(
+        () => `String ${JSON.stringify(value)} must match ${this.pattern}`,
+        `match the pattern ${this.pattern.toSource()}`
+      );
+    }
+
+    if (this.format) {
+      try {
+        r.value = this.format(r.value, context);
+      } catch (e) {
+        return context.error(
+          String(e),
+          `match the format "${this.format.name}"`
+        );
+      }
+    }
+
+    return r;
+  }
+
+  checkBaseType(baseType) {
+    return baseType == "string";
+  }
+
+  getDescriptor(path, context) {
+    if (this.enumeration) {
+      let obj = Cu.createObjectIn(context.cloneScope);
+
+      for (let e of this.enumeration) {
+        obj[e.toUpperCase()] = e;
+      }
+
+      return {
+        descriptor: { value: obj },
+      };
+    }
+  }
+}
+
+class NullType extends Type {
+  normalize(value, context) {
+    return this.normalizeBase("null", value, context);
+  }
+
+  checkBaseType(baseType) {
+    return baseType == "null";
+  }
+}
+
+let FunctionEntry;
+let Event;
+let SubModuleType;
+
+class ObjectType extends Type {
+  static get EXTRA_PROPERTIES() {
+    return [
+      "properties",
+      "patternProperties",
+      "$import",
+      ...super.EXTRA_PROPERTIES,
+    ];
+  }
+
+  static parseSchema(root, schema, path, extraProperties = []) {
+    if ("functions" in schema) {
+      return SubModuleType.parseSchema(root, schema, path, extraProperties);
+    }
+
+    if (DEBUG && !("$extend" in schema)) {
+      // Only allow extending "properties" and "patternProperties".
+      extraProperties = [
+        "additionalProperties",
+        "isInstanceOf",
+        ...extraProperties,
+      ];
+    }
+    this.checkSchemaProperties(schema, path, extraProperties);
+
+    let imported = null;
+    if ("$import" in schema) {
+      let importPath = schema.$import;
+      let idx = importPath.indexOf(".");
+      if (idx === -1) {
+        imported = [path[0], importPath];
+      } else {
+        imported = [importPath.slice(0, idx), importPath.slice(idx + 1)];
+      }
+    }
+
+    let parseProperty = (schema, extraProps = []) => {
+      return {
+        type: root.parseSchema(
+          schema,
+          path,
+          DEBUG && [
+            "unsupported",
+            "onError",
+            "permissions",
+            "default",
+            ...extraProps,
+          ]
+        ),
+        optional: schema.optional || false,
+        unsupported: schema.unsupported || false,
+        onError: schema.onError || null,
+        default: schema.default === undefined ? null : schema.default,
+      };
+    };
+
+    // Parse explicit "properties" object.
+    let properties = Object.create(null);
+    for (let propName of Object.keys(schema.properties || {})) {
+      properties[propName] = parseProperty(schema.properties[propName], [
+        "optional",
+      ]);
+    }
+
+    // Parse regexp properties from "patternProperties" object.
+    let patternProperties = [];
+    for (let propName of Object.keys(schema.patternProperties || {})) {
+      let pattern;
+      try {
+        pattern = parsePattern(propName);
+      } catch (e) {
+        throw new Error(
+          `Internal error: Invalid property pattern ${JSON.stringify(propName)}`
+        );
+      }
+
+      patternProperties.push({
+        pattern,
+        type: parseProperty(schema.patternProperties[propName]),
+      });
+    }
+
+    // Parse "additionalProperties" schema.
+    let additionalProperties = null;
+    if (schema.additionalProperties) {
+      let type = schema.additionalProperties;
+      if (type === true) {
+        type = { type: "any" };
+      }
+
+      additionalProperties = root.parseSchema(type, path);
+    }
+
+    return new this(
+      schema,
+      properties,
+      additionalProperties,
+      patternProperties,
+      schema.isInstanceOf || null,
+      imported
+    );
+  }
+
+  constructor(
+    schema,
+    properties,
+    additionalProperties,
+    patternProperties,
+    isInstanceOf,
+    imported
+  ) {
+    super(schema);
+    this.properties = properties;
+    this.additionalProperties = additionalProperties;
+    this.patternProperties = patternProperties;
+    this.isInstanceOf = isInstanceOf;
+
+    if (imported) {
+      let [ns, path] = imported;
+      ns = Schemas.getNamespace(ns);
+      let importedType = ns.get(path);
+      if (!importedType) {
+        throw new Error(`Internal error: imported type ${path} not found`);
+      }
+
+      if (DEBUG && !(importedType instanceof ObjectType)) {
+        throw new Error(
+          `Internal error: cannot import non-object type ${path}`
+        );
+      }
+
+      this.properties = Object.assign(
+        {},
+        importedType.properties,
+        this.properties
+      );
+      this.patternProperties = [
+        ...importedType.patternProperties,
+        ...this.patternProperties,
+      ];
+      this.additionalProperties =
+        importedType.additionalProperties || this.additionalProperties;
+    }
+  }
+
+  extend(type) {
+    for (let key of Object.keys(type.properties)) {
+      if (key in this.properties) {
+        throw new Error(
+          `InternalError: Attempt to extend an object with conflicting property "${key}"`
+        );
+      }
+      this.properties[key] = type.properties[key];
+    }
+
+    this.patternProperties.push(...type.patternProperties);
+
+    return this;
+  }
+
+  checkBaseType(baseType) {
+    return baseType == "object";
+  }
+
+  /**
+   * Extracts the enumerable properties of the given object, including
+   * function properties which would normally be omitted by X-ray
+   * wrappers.
+   *
+   * @param {object} value
+   * @param {Context} context
+   *        The current parse context.
+   * @returns {object}
+   *        An object with an `error` or `value` property.
+   */
+  extractProperties(value, context) {
+    // |value| should be a JS Xray wrapping an object in the
+    // extension compartment. This works well except when we need to
+    // access callable properties on |value| since JS Xrays don't
+    // support those. To work around the problem, we verify that
+    // |value| is a plain JS object (i.e., not anything scary like a
+    // Proxy). Then we copy the properties out of it into a normal
+    // object using a waiver wrapper.
+
+    let klass = ChromeUtils.getClassName(value, true);
+    if (klass != "Object") {
+      throw context.error(
+        `Expected a plain JavaScript object, got a ${klass}`,
+        `be a plain JavaScript object`
+      );
+    }
+
+    return ChromeUtils.shallowClone(value);
+  }
+
+  checkProperty(context, prop, propType, result, properties, remainingProps) {
+    let { type, optional, unsupported, onError } = propType;
+    let error = null;
+
+    if (!context.matchManifestVersion(type)) {
+      if (prop in properties) {
+        error = context.error(
+          `Property "${prop}" is unsupported in Manifest Version ${context.manifestVersion}`,
+          `not contain an unsupported "${prop}" property`
+        );
+
+        context.logWarning(forceString(error.error));
+        if (this.additionalProperties) {
+          // When `additionalProperties` is set to UnrecognizedProperty, the
+          // caller (i.e. ObjectType's normalize method) assigns the original
+          // value to `result[prop]`. Erase the property now to prevent
+          // `result[prop]` from becoming anything other than `undefined.
+          //
+          // A warning was already logged above, so we do not need to also log
+          // "An unexpected property was found in the WebExtension manifest."
+          remainingProps.delete(prop);
+        }
+        // When `additionalProperties` is not set, ObjectType's normalize method
+        // will return an error because prop is still in remainingProps.
+        return;
+      }
+    } else if (unsupported) {
+      if (prop in properties) {
+        error = context.error(
+          `Property "${prop}" is unsupported by Firefox`,
+          `not contain an unsupported "${prop}" property`
+        );
+      }
+    } else if (prop in properties) {
+      if (
+        optional &&
+        (properties[prop] === null || properties[prop] === undefined)
+      ) {
+        result[prop] = propType.default;
+      } else {
+        let r = context.withPath(prop, () =>
+          type.normalize(properties[prop], context)
+        );
+        if (r.error) {
+          error = r;
+        } else {
+          result[prop] = r.value;
+          properties[prop] = r.value;
+        }
+      }
+      remainingProps.delete(prop);
+    } else if (!optional) {
+      error = context.error(
+        `Property "${prop}" is required`,
+        `contain the required "${prop}" property`
+      );
+    } else if (optional !== "omit-key-if-missing") {
+      result[prop] = propType.default;
+    }
+
+    if (error) {
+      if (onError == "warn") {
+        context.logWarning(forceString(error.error));
+      } else if (onError != "ignore") {
+        throw error;
+      }
+
+      result[prop] = propType.default;
+    }
+  }
+
+  normalize(value, context) {
+    try {
+      let v = this.normalizeBase("object", value, context);
+      if (v.error) {
+        return v;
+      }
+      value = v.value;
+
+      if (this.isInstanceOf) {
+        if (DEBUG) {
+          if (
+            Object.keys(this.properties).length ||
+            this.patternProperties.length ||
+            !(this.additionalProperties instanceof AnyType)
+          ) {
+            throw new Error(
+              "InternalError: isInstanceOf can only be used " +
+                "with objects that are otherwise unrestricted"
+            );
+          }
+        }
+
+        if (
+          ChromeUtils.getClassName(value) !== this.isInstanceOf &&
+          (this.isInstanceOf !== "Element" || value.nodeType !== 1)
+        ) {
+          return context.error(
+            `Object must be an instance of ${this.isInstanceOf}`,
+            `be an instance of ${this.isInstanceOf}`
+          );
+        }
+
+        // This is kind of a hack, but we can't normalize things that
+        // aren't JSON, so we just return them.
+        return this.postprocess({ value }, context);
+      }
+
+      let properties = this.extractProperties(value, context);
+      let remainingProps = new Set(Object.keys(properties));
+
+      let result = {};
+      for (let prop of Object.keys(this.properties)) {
+        this.checkProperty(
+          context,
+          prop,
+          this.properties[prop],
+          result,
+          properties,
+          remainingProps
+        );
+      }
+
+      for (let prop of Object.keys(properties)) {
+        for (let { pattern, type } of this.patternProperties) {
+          if (pattern.test(prop)) {
+            this.checkProperty(
+              context,
+              prop,
+              type,
+              result,
+              properties,
+              remainingProps
+            );
+          }
+        }
+      }
+
+      if (this.additionalProperties) {
+        for (let prop of remainingProps) {
+          let r = context.withPath(prop, () =>
+            this.additionalProperties.normalize(properties[prop], context)
+          );
+          if (r.error) {
+            return r;
+          }
+          result[prop] = r.value;
+        }
+      } else if (remainingProps.size == 1) {
+        return context.error(
+          `Unexpected property "${[...remainingProps]}"`,
+          `not contain an unexpected "${[...remainingProps]}" property`
+        );
+      } else if (remainingProps.size) {
+        let props = [...remainingProps].sort().join(", ");
+        return context.error(
+          `Unexpected properties: ${props}`,
+          `not contain the unexpected properties [${props}]`
+        );
+      }
+
+      return this.postprocess({ value: result }, context);
+    } catch (e) {
+      if (e.error) {
+        return e;
+      }
+      throw e;
+    }
+  }
+}
+
+// This type is just a placeholder to be referred to by
+// SubModuleProperty. No value is ever expected to have this type.
+SubModuleType = class SubModuleType extends Type {
+  static get EXTRA_PROPERTIES() {
+    return ["functions", "events", "properties", ...super.EXTRA_PROPERTIES];
+  }
+
+  static parseSchema(root, schema, path, extraProperties = []) {
+    this.checkSchemaProperties(schema, path, extraProperties);
+
+    // The path we pass in here is only used for error messages.
+    path = [...path, schema.id];
+    let functions = schema.functions
+      .filter(fun => !fun.unsupported)
+      .map(fun => FunctionEntry.parseSchema(root, fun, path));
+
+    let events = [];
+
+    if (schema.events) {
+      events = schema.events
+        .filter(event => !event.unsupported)
+        .map(event => Event.parseSchema(root, event, path));
+    }
+
+    return new this(schema, functions, events);
+  }
+
+  constructor(schema, functions, events) {
+    // schema contains properties such as min/max_manifest_version needed
+    // in the base class so that the Context class can version compare
+    // any entries against the manifest version.
+    super(schema);
+    this.functions = functions;
+    this.events = events;
+  }
+};
+
+class NumberType extends Type {
+  normalize(value, context) {
+    let r = this.normalizeBase("number", value, context);
+    if (r.error) {
+      return r;
+    }
+
+    if (isNaN(r.value) || !Number.isFinite(r.value)) {
+      return context.error(
+        "NaN and infinity are not valid",
+        "be a finite number"
+      );
+    }
+
+    return r;
+  }
+
+  checkBaseType(baseType) {
+    return baseType == "number" || baseType == "integer";
+  }
+}
+
+class IntegerType extends Type {
+  static get EXTRA_PROPERTIES() {
+    return ["minimum", "maximum", ...super.EXTRA_PROPERTIES];
+  }
+
+  static parseSchema(root, schema, path, extraProperties = []) {
+    this.checkSchemaProperties(schema, path, extraProperties);
+
+    let { minimum = -Infinity, maximum = Infinity } = schema;
+    return new this(schema, minimum, maximum);
+  }
+
+  constructor(schema, minimum, maximum) {
+    super(schema);
+    this.minimum = minimum;
+    this.maximum = maximum;
+  }
+
+  normalize(value, context) {
+    let r = this.normalizeBase("integer", value, context);
+    if (r.error) {
+      return r;
+    }
+    value = r.value;
+
+    // Ensure it's between -2**31 and 2**31-1
+    if (!Number.isSafeInteger(value)) {
+      return context.error(
+        "Integer is out of range",
+        "be a valid 32 bit signed integer"
+      );
+    }
+
+    if (value < this.minimum) {
+      return context.error(
+        `Integer ${value} is too small (must be at least ${this.minimum})`,
+        `be at least ${this.minimum}`
+      );
+    }
+    if (value > this.maximum) {
+      return context.error(
+        `Integer ${value} is too big (must be at most ${this.maximum})`,
+        `be no greater than ${this.maximum}`
+      );
+    }
+
+    return this.postprocess(r, context);
+  }
+
+  checkBaseType(baseType) {
+    return baseType == "integer";
+  }
+}
+
+class BooleanType extends Type {
+  static get EXTRA_PROPERTIES() {
+    return ["enum", ...super.EXTRA_PROPERTIES];
+  }
+
+  static parseSchema(root, schema, path, extraProperties = []) {
+    this.checkSchemaProperties(schema, path, extraProperties);
+    let enumeration = schema.enum || null;
+    return new this(schema, enumeration);
+  }
+
+  constructor(schema, enumeration) {
+    super(schema);
+    this.enumeration = enumeration;
+  }
+
+  normalize(value, context) {
+    if (!this.checkBaseType(getValueBaseType(value))) {
+      return context.error(
+        () => `Expected boolean instead of ${JSON.stringify(value)}`,
+        `be a boolean`
+      );
+    }
+    value = this.preprocess(value, context);
+    if (this.enumeration && !this.enumeration.includes(value)) {
+      return context.error(
+        () => `Invalid value ${JSON.stringify(value)}`,
+        `be ${this.enumeration}`
+      );
+    }
+    this.checkDeprecated(context, value);
+    return { value };
+  }
+
+  checkBaseType(baseType) {
+    return baseType == "boolean";
+  }
+}
+
+class ArrayType extends Type {
+  static get EXTRA_PROPERTIES() {
+    return ["items", "minItems", "maxItems", ...super.EXTRA_PROPERTIES];
+  }
+
+  static parseSchema(root, schema, path, extraProperties = []) {
+    this.checkSchemaProperties(schema, path, extraProperties);
+
+    let items = root.parseSchema(schema.items, path, ["onError"]);
+
+    return new this(
+      schema,
+      items,
+      schema.minItems || 0,
+      schema.maxItems || Infinity
+    );
+  }
+
+  constructor(schema, itemType, minItems, maxItems) {
+    super(schema);
+    this.itemType = itemType;
+    this.minItems = minItems;
+    this.maxItems = maxItems;
+    this.onError = schema.items.onError || null;
+  }
+
+  normalize(value, context) {
+    let v = this.normalizeBase("array", value, context);
+    if (v.error) {
+      return v;
+    }
+    value = v.value;
+
+    let result = [];
+    for (let [i, element] of value.entries()) {
+      element = context.withPath(String(i), () =>
+        this.itemType.normalize(element, context)
+      );
+      if (element.error) {
+        if (this.onError == "warn") {
+          context.logWarning(forceString(element.error));
+        } else if (this.onError != "ignore") {
+          return element;
+        }
+        continue;
+      }
+      result.push(element.value);
+    }
+
+    if (result.length < this.minItems) {
+      return context.error(
+        `Array requires at least ${this.minItems} items; you have ${result.length}`,
+        `have at least ${this.minItems} items`
+      );
+    }
+
+    if (result.length > this.maxItems) {
+      return context.error(
+        `Array requires at most ${this.maxItems} items; you have ${result.length}`,
+        `have at most ${this.maxItems} items`
+      );
+    }
+
+    return this.postprocess({ value: result }, context);
+  }
+
+  checkBaseType(baseType) {
+    return baseType == "array";
+  }
+}
+
+class FunctionType extends Type {
+  static get EXTRA_PROPERTIES() {
+    return [
+      "parameters",
+      "async",
+      "returns",
+      "requireUserInput",
+      ...super.EXTRA_PROPERTIES,
+    ];
+  }
+
+  static parseSchema(root, schema, path, extraProperties = []) {
+    this.checkSchemaProperties(schema, path, extraProperties);
+
+    let isAsync = !!schema.async;
+    let isExpectingCallback = typeof schema.async === "string";
+    let parameters = null;
+    if ("parameters" in schema) {
+      parameters = [];
+      for (let param of schema.parameters) {
+        // Callbacks default to optional for now, because of promise
+        // handling.
+        let isCallback = isAsync && param.name == schema.async;
+        if (isCallback) {
+          isExpectingCallback = false;
+        }
+
+        parameters.push({
+          type: root.parseSchema(param, path, ["name", "optional", "default"]),
+          name: param.name,
+          optional: param.optional == null ? isCallback : param.optional,
+          default: param.default == undefined ? null : param.default,
+        });
+      }
+    }
+    let hasAsyncCallback = false;
+    if (isAsync) {
+      hasAsyncCallback =
+        parameters &&
+        parameters.length &&
+        parameters[parameters.length - 1].name == schema.async;
+    }
+
+    if (DEBUG) {
+      if (isExpectingCallback) {
+        throw new Error(
+          `Internal error: Expected a callback parameter ` +
+            `with name ${schema.async}`
+        );
+      }
+
+      if (isAsync && schema.returns) {
+        throw new Error(
+          "Internal error: Async functions must not have return values."
+        );
+      }
+      if (
+        isAsync &&
+        schema.allowAmbiguousOptionalArguments &&
+        !hasAsyncCallback
+      ) {
+        throw new Error(
+          "Internal error: Async functions with ambiguous " +
+            "arguments must declare the callback as the last parameter"
+        );
+      }
+    }
+
+    return new this(
+      schema,
+      parameters,
+      isAsync,
+      hasAsyncCallback,
+      !!schema.requireUserInput
+    );
+  }
+
+  constructor(schema, parameters, isAsync, hasAsyncCallback, requireUserInput) {
+    super(schema);
+    this.parameters = parameters;
+    this.isAsync = isAsync;
+    this.hasAsyncCallback = hasAsyncCallback;
+    this.requireUserInput = requireUserInput;
+  }
+
+  normalize(value, context) {
+    return this.normalizeBase("function", value, context);
+  }
+
+  checkBaseType(baseType) {
+    return baseType == "function";
+  }
+}
+
+// Represents a "property" defined in a schema namespace with a
+// particular value. Essentially this is a constant.
+class ValueProperty extends Entry {
+  constructor(schema, name, value) {
+    super(schema);
+    this.name = name;
+    this.value = value;
+  }
+
+  getDescriptor(path, context) {
+    // Prevent injection if not a supported version.
+    if (!context.matchManifestVersion(this)) {
+      return;
+    }
+
+    return {
+      descriptor: { value: this.value },
+    };
+  }
+}
+
+// Represents a "property" defined in a schema namespace that is not a
+// constant.
+class TypeProperty extends Entry {
+  unsupported = false;
+
+  constructor(schema, path, name, type, writable, permissions) {
+    super(schema);
+    this.path = path;
+    this.name = name;
+    this.type = type;
+    this.writable = writable;
+    this.permissions = permissions;
+  }
+
+  throwError(context, msg) {
+    throw context.makeError(`${msg} for ${this.path.join(".")}.${this.name}.`);
+  }
+
+  getDescriptor(path, context) {
+    if (this.unsupported || !context.matchManifestVersion(this)) {
+      return;
+    }
+
+    let apiImpl = context.getImplementation(path.join("."), this.name);
+
+    let getStub = () => {
+      this.checkDeprecated(context);
+      return apiImpl.getProperty();
+    };
+
+    let descriptor = {
+      get: Cu.exportFunction(getStub, context.cloneScope),
+    };
+
+    if (this.writable) {
+      let setStub = value => {
+        let normalized = this.type.normalize(value, context);
+        if (normalized.error) {
+          this.throwError(context, forceString(normalized.error));
+        }
+
+        apiImpl.setProperty(normalized.value);
+      };
+
+      descriptor.set = Cu.exportFunction(setStub, context.cloneScope);
+    }
+
+    return {
+      descriptor,
+      revoke() {
+        apiImpl.revoke();
+        apiImpl = null;
+      },
+    };
+  }
+}
+
+class SubModuleProperty extends Entry {
+  // A SubModuleProperty represents a tree of objects and properties
+  // to expose to an extension. Currently we support only a limited
+  // form of sub-module properties, where "$ref" points to a
+  // SubModuleType containing a list of functions and "properties" is
+  // a list of additional simple properties.
+  //
+  // name: Name of the property stuff is being added to.
+  // namespaceName: Namespace in which the property lives.
+  // reference: Name of the type defining the functions to add to the property.
+  // properties: Additional properties to add to the module (unsupported).
+  constructor(root, schema, path, name, reference, properties, permissions) {
+    super(schema);
+    this.root = root;
+    this.name = name;
+    this.path = path;
+    this.namespaceName = path.join(".");
+    this.reference = reference;
+    this.properties = properties;
+    this.permissions = permissions;
+  }
+
+  get targetType() {
+    let ns = this.root.getNamespace(this.namespaceName);
+    let type = ns.get(this.reference);
+    if (!type && this.reference.includes(".")) {
+      let [namespaceName, ref] = this.reference.split(".");
+      ns = this.root.getNamespace(namespaceName);
+      type = ns.get(ref);
+    }
+    return type;
+  }
+
+  getDescriptor(path, context) {
+    let obj = Cu.createObjectIn(context.cloneScope);
+
+    let ns = this.root.getNamespace(this.namespaceName);
+    let type = this.targetType;
+
+    // Prevent injection if not a supported version.
+    if (!context.matchManifestVersion(type)) {
+      return;
+    }
+
+    if (DEBUG) {
+      if (!type || !(type instanceof SubModuleType)) {
+        throw new Error(
+          `Internal error: ${this.namespaceName}.${this.reference} ` +
+            `is not a sub-module`
+        );
+      }
+    }
+    let subpath = [...path, this.name];
+
+    let functions = type.functions;
+    for (let fun of functions) {
+      context.injectInto(fun, obj, fun.name, subpath, ns);
+    }
+
+    let events = type.events;
+    for (let event of events) {
+      context.injectInto(event, obj, event.name, subpath, ns);
+    }
+
+    // TODO: Inject this.properties.
+
+    return {
+      descriptor: { value: obj },
+      revoke() {
+        let unwrapped = ChromeUtils.waiveXrays(obj);
+        for (let fun of functions) {
+          try {
+            delete unwrapped[fun.name];
+          } catch (e) {
+            Cu.reportError(e);
+          }
+        }
+      },
+    };
+  }
+}
+
+// This class is a base class for FunctionEntrys and Events. It takes
+// care of validating parameter lists (i.e., handling of optional
+// parameters and parameter type checking).
+class CallEntry extends Entry {
+  hasAsyncCallback = false;
+
+  constructor(schema, path, name, parameters, allowAmbiguousOptionalArguments) {
+    super(schema);
+    this.path = path;
+    this.name = name;
+    this.parameters = parameters;
+    this.allowAmbiguousOptionalArguments = allowAmbiguousOptionalArguments;
+  }
+
+  throwError(context, msg) {
+    throw context.makeError(`${msg} for ${this.path.join(".")}.${this.name}.`);
+  }
+
+  checkParameters(args, context) {
+    let fixedArgs = [];
+
+    // First we create a new array, fixedArgs, that is the same as
+    // |args| but with default values in place of omitted optional parameters.
+    let check = (parameterIndex, argIndex) => {
+      if (parameterIndex == this.parameters.length) {
+        if (argIndex == args.length) {
+          return true;
+        }
+        return false;
+      }
+
+      let parameter = this.parameters[parameterIndex];
+      if (parameter.optional) {
+        // Try skipping it.
+        fixedArgs[parameterIndex] = parameter.default;
+        if (check(parameterIndex + 1, argIndex)) {
+          return true;
+        }
+      }
+
+      if (argIndex == args.length) {
+        return false;
+      }
+
+      let arg = args[argIndex];
+      if (!parameter.type.checkBaseType(getValueBaseType(arg))) {
+        // For Chrome compatibility, use the default value if null or undefined
+        // is explicitly passed but is not a valid argument in this position.
+        if (parameter.optional && (arg === null || arg === undefined)) {
+          fixedArgs[parameterIndex] = Cu.cloneInto(parameter.default, {});
+        } else {
+          return false;
+        }
+      } else {
+        fixedArgs[parameterIndex] = arg;
+      }
+
+      return check(parameterIndex + 1, argIndex + 1);
+    };
+
+    if (this.allowAmbiguousOptionalArguments) {
+      // When this option is set, it's up to the implementation to
+      // parse arguments.
+      // The last argument for asynchronous methods is either a function or null.
+      // This is specifically done for runtime.sendMessage.
+      if (this.hasAsyncCallback && typeof args[args.length - 1] != "function") {
+        args.push(null);
+      }
+      return args;
+    }
+    let success = check(0, 0);
+    if (!success) {
+      this.throwError(context, "Incorrect argument types");
+    }
+
+    // Now we normalize (and fully type check) all non-omitted arguments.
+    fixedArgs = fixedArgs.map((arg, parameterIndex) => {
+      if (arg === null) {
+        return null;
+      }
+      let parameter = this.parameters[parameterIndex];
+      let r = parameter.type.normalize(arg, context);
+      if (r.error) {
+        this.throwError(
+          context,
+          `Type error for parameter ${parameter.name} (${forceString(r.error)})`
+        );
+      }
+      return r.value;
+    });
+
+    return fixedArgs;
+  }
+}
+
+// Represents a "function" defined in a schema namespace.
+FunctionEntry = class FunctionEntry extends CallEntry {
+  static parseSchema(root, schema, path) {
+    // When not in DEBUG mode, we just need to know *if* this returns.
+    /** @type {boolean|object} */
+    let returns = !!schema.returns;
+    if (DEBUG && "returns" in schema) {
+      returns = {
+        type: root.parseSchema(schema.returns, path, ["optional", "name"]),
+        optional: schema.returns.optional || false,
+        name: "result",
+      };
+    }
+
+    return new this(
+      schema,
+      path,
+      schema.name,
+      root.parseSchema(schema, path, [
+        "name",
+        "unsupported",
+        "returns",
+        "permissions",
+        "allowAmbiguousOptionalArguments",
+        "allowCrossOriginArguments",
+      ]),
+      schema.unsupported || false,
+      schema.allowAmbiguousOptionalArguments || false,
+      schema.allowCrossOriginArguments || false,
+      returns,
+      schema.permissions || null
+    );
+  }
+
+  constructor(
+    schema,
+    path,
+    name,
+    type,
+    unsupported,
+    allowAmbiguousOptionalArguments,
+    allowCrossOriginArguments,
+    returns,
+    permissions
+  ) {
+    super(schema, path, name, type.parameters, allowAmbiguousOptionalArguments);
+    this.unsupported = unsupported;
+    this.returns = returns;
+    this.permissions = permissions;
+    this.allowCrossOriginArguments = allowCrossOriginArguments;
+
+    this.isAsync = type.isAsync;
+    this.hasAsyncCallback = type.hasAsyncCallback;
+    this.requireUserInput = type.requireUserInput;
+  }
+
+  checkValue({ type, optional, name }, value, context) {
+    if (optional && value == null) {
+      return;
+    }
+    if (
+      type.reference === "ExtensionPanel" ||
+      type.reference === "ExtensionSidebarPane" ||
+      type.reference === "Port"
+    ) {
+      // TODO: We currently treat objects with functions as SubModuleType,
+      // which is just wrong, and a bigger yak.  Skipping for now.
+      return;
+    }
+    const { error } = type.normalize(value, context);
+    if (error) {
+      this.throwError(
+        context,
+        `Type error for ${name} value (${forceString(error)})`
+      );
+    }
+  }
+
+  checkCallback(args, context) {
+    const callback = this.parameters[this.parameters.length - 1];
+    for (const [i, param] of callback.type.parameters.entries()) {
+      this.checkValue(param, args[i], context);
+    }
+  }
+
+  getDescriptor(path, context) {
+    let apiImpl = context.getImplementation(path.join("."), this.name);
+
+    let stub;
+    if (this.isAsync) {
+      stub = (...args) => {
+        this.checkDeprecated(context);
+        let actuals = this.checkParameters(args, context);
+        let callback = null;
+        if (this.hasAsyncCallback) {
+          callback = actuals.pop();
+        }
+        if (callback === null && context.isChromeCompat) {
+          // We pass an empty stub function as a default callback for
+          // the `chrome` API, so promise objects are not returned,
+          // and lastError values are reported immediately.
+          callback = () => {};
+        }
+        if (DEBUG && this.hasAsyncCallback && callback) {
+          let original = callback;
+          callback = (...args) => {
+            this.checkCallback(args, context);
+            original(...args);
+          };
+        }
+        let result = apiImpl.callAsyncFunction(
+          actuals,
+          callback,
+          this.requireUserInput
+        );
+        if (DEBUG && this.hasAsyncCallback && !callback) {
+          return result.then(result => {
+            this.checkCallback([result], context);
+            return result;
+          });
+        }
+        return result;
+      };
+    } else if (!this.returns) {
+      stub = (...args) => {
+        this.checkDeprecated(context);
+        let actuals = this.checkParameters(args, context);
+        return apiImpl.callFunctionNoReturn(actuals);
+      };
+    } else {
+      stub = (...args) => {
+        this.checkDeprecated(context);
+        let actuals = this.checkParameters(args, context);
+        let result = apiImpl.callFunction(actuals);
+        if (DEBUG && this.returns) {
+          this.checkValue(this.returns, result, context);
+        }
+        return result;
+      };
+    }
+
+    return {
+      descriptor: {
+        value: Cu.exportFunction(stub, context.cloneScope, {
+          allowCrossOriginArguments: this.allowCrossOriginArguments,
+        }),
+      },
+      revoke() {
+        apiImpl.revoke();
+        apiImpl = null;
+      },
+    };
+  }
+};
+
+// Represents an "event" defined in a schema namespace.
+//
+// TODO Bug 1369722: we should be able to remove the eslint-disable-line that follows
+// once Bug 1369722 has been fixed.
+// eslint-disable-next-line no-global-assign
+Event = class Event extends CallEntry {
+  static parseSchema(root, event, path) {
+    let extraParameters = Array.from(event.extraParameters || [], param => ({
+      type: root.parseSchema(param, path, ["name", "optional", "default"]),
+      name: param.name,
+      optional: param.optional || false,
+      default: param.default == undefined ? null : param.default,
+    }));
+
+    let extraProperties = [
+      "name",
+      "unsupported",
+      "permissions",
+      "extraParameters",
+      // We ignore these properties for now.
+      "returns",
+      "filters",
+    ];
+
+    return new this(
+      event,
+      path,
+      event.name,
+      root.parseSchema(event, path, extraProperties),
+      extraParameters,
+      event.unsupported || false,
+      event.permissions || null
+    );
+  }
+
+  constructor(
+    schema,
+    path,
+    name,
+    type,
+    extraParameters,
+    unsupported,
+    permissions
+  ) {
+    super(schema, path, name, extraParameters);
+    this.type = type;
+    this.unsupported = unsupported;
+    this.permissions = permissions;
+  }
+
+  checkListener(listener, context) {
+    let r = this.type.normalize(listener, context);
+    if (r.error) {
+      this.throwError(context, "Invalid listener");
+    }
+    return r.value;
+  }
+
+  getDescriptor(path, context) {
+    let apiImpl = context.getImplementation(path.join("."), this.name);
+
+    let addStub = (listener, ...args) => {
+      listener = this.checkListener(listener, context);
+      let actuals = this.checkParameters(args, context);
+      apiImpl.addListener(listener, actuals);
+    };
+
+    let removeStub = listener => {
+      listener = this.checkListener(listener, context);
+      apiImpl.removeListener(listener);
+    };
+
+    let hasStub = listener => {
+      listener = this.checkListener(listener, context);
+      return apiImpl.hasListener(listener);
+    };
+
+    let obj = Cu.createObjectIn(context.cloneScope);
+
+    Cu.exportFunction(addStub, obj, { defineAs: "addListener" });
+    Cu.exportFunction(removeStub, obj, { defineAs: "removeListener" });
+    Cu.exportFunction(hasStub, obj, { defineAs: "hasListener" });
+
+    return {
+      descriptor: { value: obj },
+      revoke() {
+        apiImpl.revoke();
+        apiImpl = null;
+
+        let unwrapped = ChromeUtils.waiveXrays(obj);
+        delete unwrapped.addListener;
+        delete unwrapped.removeListener;
+        delete unwrapped.hasListener;
+      },
+    };
+  }
+};
+
+const TYPES = Object.freeze(
+  Object.assign(Object.create(null), {
+    any: AnyType,
+    array: ArrayType,
+    boolean: BooleanType,
+    function: FunctionType,
+    integer: IntegerType,
+    null: NullType,
+    number: NumberType,
+    object: ObjectType,
+    string: StringType,
+  })
+);
+
+const LOADERS = {
+  events: "loadEvent",
+  functions: "loadFunction",
+  properties: "loadProperty",
+  types: "loadType",
+};
+
+class Namespace extends Map {
+  constructor(root, name, path) {
+    super();
+
+    this.root = root;
+
+    this._lazySchemas = [];
+    this.initialized = false;
+
+    this.name = name;
+    this.path = name ? [...path, name] : [...path];
+
+    this.superNamespace = null;
+
+    this.min_manifest_version = MIN_MANIFEST_VERSION;
+    this.max_manifest_version = MAX_MANIFEST_VERSION;
+
+    this.permissions = null;
+    this.allowedContexts = [];
+    this.defaultContexts = [];
+  }
+
+  /**
+   * Adds a JSON Schema object to the set of schemas that represent this
+   * namespace.
+   *
+   * @param {object} schema
+   *        A JSON schema object which partially describes this
+   *        namespace.
+   */
+  addSchema(schema) {
+    this._lazySchemas.push(schema);
+
+    for (let prop of [
+      "permissions",
+      "allowedContexts",
+      "defaultContexts",
+      "min_manifest_version",
+      "max_manifest_version",
+    ]) {
+      if (schema[prop]) {
+        this[prop] = schema[prop];
+      }
+    }
+
+    if (schema.$import) {
+      this.superNamespace = this.root.getNamespace(schema.$import);
+    }
+  }
+
+  /**
+   * Initializes the keys of this namespace based on the schema objects
+   * added via previous `addSchema` calls.
+   */
+  init() {
+    if (this.initialized) {
+      return;
+    }
+
+    if (this.superNamespace) {
+      this._lazySchemas.unshift(...this.superNamespace._lazySchemas);
+    }
+
+    // Keep in sync with LOADERS above.
+    this.types = new DefaultMap(() => []);
+    this.properties = new DefaultMap(() => []);
+    this.functions = new DefaultMap(() => []);
+    this.events = new DefaultMap(() => []);
+
+    for (let schema of this._lazySchemas) {
+      for (let type of schema.types || []) {
+        if (!type.unsupported) {
+          this.types.get(type.$extend || type.id).push(type);
+        }
+      }
+
+      for (let [name, prop] of Object.entries(schema.properties || {})) {
+        if (!prop.unsupported) {
+          this.properties.get(name).push(prop);
+        }
+      }
+
+      for (let fun of schema.functions || []) {
+        if (!fun.unsupported) {
+          this.functions.get(fun.name).push(fun);
+        }
+      }
+
+      for (let event of schema.events || []) {
+        if (!event.unsupported) {
+          this.events.get(event.name).push(event);
+        }
+      }
+    }
+
+    // For each type of top-level property in the schema object, iterate
+    // over all properties of that type, and create a temporary key for
+    // each property pointing to its type. Those temporary properties
+    // are later used to instantiate an Entry object based on the actual
+    // schema object.
+    for (let type of Object.keys(LOADERS)) {
+      for (let key of this[type].keys()) {
+        this.set(key, type);
+      }
+    }
+
+    this.initialized = true;
+
+    if (DEBUG) {
+      for (let key of this.keys()) {
+        this.get(key);
+      }
+    }
+  }
+
+  /**
+   * Initializes the value of a given key, by parsing the schema object
+   * associated with it and replacing its temporary value with an `Entry`
+   * instance.
+   *
+   * @param {string} key
+   *        The name of the property to initialize.
+   * @param {string} type
+   *        The type of property the key represents. Must have a
+   *        corresponding entry in the `LOADERS` object, pointing to the
+   *        initialization method for that type.
+   *
+   * @returns {Entry}
+   */
+  initKey(key, type) {
+    let loader = LOADERS[type];
+
+    for (let schema of this[type].get(key)) {
+      this.set(key, this[loader](key, schema));
+    }
+
+    return this.get(key);
+  }
+
+  loadType(name, type) {
+    if ("$extend" in type) {
+      return this.extendType(type);
+    }
+    return this.root.parseSchema(type, this.path, ["id"]);
+  }
+
+  extendType(type) {
+    let targetType = this.get(type.$extend);
+
+    // Only allow extending object and choices types for now.
+    if (targetType instanceof ObjectType) {
+      type.type = "object";
+    } else if (DEBUG) {
+      if (!targetType) {
+        throw new Error(
+          `Internal error: Attempt to extend a nonexistent type ${type.$extend}`
+        );
+      } else if (!(targetType instanceof ChoiceType)) {
+        throw new Error(
+          `Internal error: Attempt to extend a non-extensible type ${type.$extend}`
+        );
+      }
+    }
+
+    let parsed = this.root.parseSchema(type, this.path, ["$extend"]);
+
+    if (DEBUG && parsed.constructor !== targetType.constructor) {
+      throw new Error(`Internal error: Bad attempt to extend ${type.$extend}`);
+    }
+
+    targetType.extend(parsed);
+
+    return targetType;
+  }
+
+  loadProperty(name, prop) {
+    if ("$ref" in prop) {
+      if (!prop.unsupported) {
+        return new SubModuleProperty(
+          this.root,
+          prop,
+          this.path,
+          name,
+          prop.$ref,
+          prop.properties || {},
+          prop.permissions || null
+        );
+      }
+    } else if ("value" in prop) {
+      return new ValueProperty(prop, name, prop.value);
+    } else {
+      // We ignore the "optional" attribute on properties since we
+      // don't inject anything here anyway.
+      let type = this.root.parseSchema(
+        prop,
+        [this.name],
+        ["optional", "permissions", "writable"]
+      );
+      return new TypeProperty(
+        prop,
+        this.path,
+        name,
+        type,
+        prop.writable || false,
+        prop.permissions || null
+      );
+    }
+  }
+
+  loadFunction(name, fun) {
+    return FunctionEntry.parseSchema(this.root, fun, this.path);
+  }
+
+  loadEvent(name, event) {
+    return Event.parseSchema(this.root, event, this.path);
+  }
+
+  /**
+   * Injects the properties of this namespace into the given object.
+   *
+   * @param {object} dest
+   *        The object into which to inject the namespace properties.
+   * @param {InjectionContext} context
+   *        The injection context with which to inject the properties.
+   */
+  injectInto(dest, context) {
+    for (let name of this.keys()) {
+      // If the entry does not match the manifest version do not
+      // inject the property.  This prevents the item from being
+      // enumerable in the namespace object.  We cannot accomplish
+      // this inside exportLazyProperty, it specifically injects
+      // an enumerable object.
+      let entry = this.get(name);
+      if (!context.matchManifestVersion(entry)) {
+        continue;
+      }
+      exportLazyProperty(dest, name, () => {
+        let entry = this.get(name);
+
+        return context.getDescriptor(entry, dest, name, this.path, this);
+      });
+    }
+  }
+
+  getDescriptor(path, context) {
+    let obj = Cu.createObjectIn(context.cloneScope);
+
+    let ns = context.schemaRoot.getNamespace(this.path.join("."));
+    ns.injectInto(obj, context);
+
+    // Only inject the namespace object if it isn't empty.
+    if (Object.keys(obj).length) {
+      return {
+        descriptor: { value: obj },
+      };
+    }
+  }
+
+  keys() {
+    this.init();
+    return super.keys();
+  }
+
+  /** @returns {Generator<[string, Entry]>} */
+  *entries() {
+    for (let key of this.keys()) {
+      yield [key, this.get(key)];
+    }
+  }
+
+  get(key) {
+    this.init();
+    let value = super.get(key);
+
+    // The initial values of lazily-initialized schema properties are
+    // strings, pointing to the type of property, corresponding to one
+    // of the entries in the `LOADERS` object.
+    if (typeof value === "string") {
+      value = this.initKey(key, value);
+    }
+
+    return value;
+  }
+
+  /**
+   * Returns a Namespace object for the given namespace name. If a
+   * namespace object with this name does not already exist, it is
+   * created. If the name contains any '.' characters, namespaces are
+   * recursively created, for each dot-separated component.
+   *
+   * @param {string} name
+   *        The name of the sub-namespace to retrieve.
+   * @param {boolean} [create = true]
+   *        If true, create any intermediate namespaces which don't
+   *        exist.
+   *
+   * @returns {Namespace}
+   */
+  getNamespace(name, create = true) {
+    let subName;
+
+    let idx = name.indexOf(".");
+    if (idx > 0) {
+      subName = name.slice(idx + 1);
+      name = name.slice(0, idx);
+    }
+
+    let ns = super.get(name);
+    if (!ns) {
+      if (!create) {
+        return null;
+      }
+      ns = new Namespace(this.root, name, this.path);
+      this.set(name, ns);
+    }
+
+    if (subName) {
+      return ns.getNamespace(subName);
+    }
+    return ns;
+  }
+
+  getOwnNamespace(name) {
+    return this.getNamespace(name);
+  }
+
+  has(key) {
+    this.init();
+    return super.has(key);
+  }
+}
+
+/**
+ * A namespace which combines the children of an arbitrary number of
+ * sub-namespaces.
+ */
+class Namespaces extends Namespace {
+  constructor(root, name, path, namespaces) {
+    super(root, name, path);
+
+    this.namespaces = namespaces;
+  }
+
+  injectInto(obj, context) {
+    for (let ns of this.namespaces) {
+      ns.injectInto(obj, context);
+    }
+  }
+}
+
+/**
+ * A root schema which combines the contents of an arbitrary number of base
+ * schema roots.
+ */
+class SchemaRoots extends Namespaces {
+  constructor(root, bases) {
+    bases = bases.map(base => base.rootSchema || base);
+
+    super(null, "", [], bases);
+
+    this.root = root;
+    this.bases = bases;
+    this._namespaces = new Map();
+  }
+
+  _getNamespace(name, create) {
+    let results = [];
+    for (let root of this.bases) {
+      let ns = root.getNamespace(name, create);
+      if (ns) {
+        results.push(ns);
+      }
+    }
+
+    if (results.length == 1) {
+      return results[0];
+    }
+
+    if (results.length) {
+      return new Namespaces(this.root, name, name.split("."), results);
+    }
+    return null;
+  }
+
+  getNamespace(name, create) {
+    let ns = this._namespaces.get(name);
+    if (!ns) {
+      ns = this._getNamespace(name, create);
+      if (ns) {
+        this._namespaces.set(name, ns);
+      }
+    }
+    return ns;
+  }
+
+  *getNamespaces(name) {
+    for (let root of this.bases) {
+      yield* root.getNamespaces(name);
+    }
+  }
+}
+
+/**
+ * A root schema namespace containing schema data which is isolated from data in
+ * other schema roots. May extend a base namespace, in which case schemas in
+ * this root may refer to types in a base, but not vice versa.
+ *
+ * @param {SchemaRoot|Array<SchemaRoot>|null} base
+ *        A base schema root (or roots) from which to derive, or null.
+ * @param {Map<string, Array|StructuredCloneHolder>} schemaJSON
+ *        A map of schema URLs and corresponding JSON blobs from which to
+ *        populate this root namespace.
+ */
+export class SchemaRoot extends Namespace {
+  constructor(base, schemaJSON) {
+    super(null, "", []);
+
+    if (Array.isArray(base)) {
+      base = new SchemaRoots(this, base);
+    }
+
+    this.root = this;
+    this.base = base;
+    this.schemaJSON = schemaJSON;
+  }
+
+  *getNamespaces(path) {
+    let name = path.join(".");
+
+    let ns = this.getNamespace(name, false);
+    if (ns) {
+      yield ns;
+    }
+
+    if (this.base) {
+      yield* this.base.getNamespaces(name);
+    }
+  }
+
+  /**
+   * Returns the sub-namespace with the given name. If the given namespace
+   * doesn't already exist, attempts to find it in the base SchemaRoot before
+   * creating a new empty namespace.
+   *
+   * @param {string} name
+   *        The namespace to retrieve.
+   * @param {boolean} [create = true]
+   *        If true, an empty namespace should be created if one does not
+   *        already exist.
+   * @returns {Namespace|null}
+   */
+  getNamespace(name, create = true) {
+    let ns = super.getNamespace(name, false);
+    if (ns) {
+      return ns;
+    }
+
+    ns = this.base && this.base.getNamespace(name, false);
+    if (ns) {
+      return ns;
+    }
+    return create && super.getNamespace(name, create);
+  }
+
+  /**
+   * Like getNamespace, but does not take the base SchemaRoot into account.
+   *
+   * @param {string} name
+   *        The namespace to retrieve.
+   * @returns {Namespace}
+   */
+  getOwnNamespace(name) {
+    return super.getNamespace(name);
+  }
+
+  parseSchema(schema, path, extraProperties = []) {
+    let allowedProperties = DEBUG && new Set(extraProperties);
+
+    if ("choices" in schema) {
+      return ChoiceType.parseSchema(this, schema, path, allowedProperties);
+    } else if ("$ref" in schema) {
+      return RefType.parseSchema(this, schema, path, allowedProperties);
+    }
+
+    let type = TYPES[schema.type];
+
+    if (DEBUG) {
+      allowedProperties.add("type");
+
+      if (!("type" in schema)) {
+        throw new Error(`Unexpected value for type: ${JSON.stringify(schema)}`);
+      }
+
+      if (!type) {
+        throw new Error(`Unexpected type ${schema.type}`);
+      }
+    }
+
+    return type.parseSchema(this, schema, path, allowedProperties);
+  }
+
+  parseSchemas() {
+    for (let [key, schema] of this.schemaJSON.entries()) {
+      try {
+        if (typeof schema.deserialize === "function") {
+          schema = schema.deserialize(globalThis, isParentProcess);
+
+          // If we're in the parent process, we need to keep the
+          // StructuredCloneHolder blob around in order to send to future child
+          // processes. If we're in a child, we have no further use for it, so
+          // just store the deserialized schema data in its place.
+          if (!isParentProcess) {
+            this.schemaJSON.set(key, schema);
+          }
+        }
+
+        this.loadSchema(schema);
+      } catch (e) {
+        Cu.reportError(e);
+      }
+    }
+  }
+
+  loadSchema(json) {
+    for (let namespace of json) {
+      this.getOwnNamespace(namespace.namespace).addSchema(namespace);
+    }
+  }
+
+  /**
+   * Checks whether a given object has the necessary permissions to
+   * expose the given namespace.
+   *
+   * @param {string} namespace
+   *        The top-level namespace to check permissions for.
+   * @param {object} wrapperFuncs
+   *        Wrapper functions for the given context.
+   * @param {Function} wrapperFuncs.hasPermission
+   *        A function which, when given a string argument, returns true
+   *        if the context has the given permission.
+   * @returns {boolean}
+   *        True if the context has permission for the given namespace.
+   */
+  checkPermissions(namespace, wrapperFuncs) {
+    let ns = this.getNamespace(namespace);
+    if (ns && ns.permissions) {
+      return ns.permissions.some(perm => wrapperFuncs.hasPermission(perm));
+    }
+    return true;
+  }
+
+  /**
+   * Inject registered extension APIs into `dest`.
+   *
+   * @param {object} dest The root namespace for the APIs.
+   *     This object is usually exposed to extensions as "chrome" or "browser".
+   * @param {object} wrapperFuncs An implementation of the InjectionContext
+   *     interface, which runs the actual functionality of the generated API.
+   */
+  inject(dest, wrapperFuncs) {
+    let context = new InjectionContext(wrapperFuncs, this);
+
+    this.injectInto(dest, context);
+  }
+
+  injectInto(dest, context) {
+    // For schema graphs where multiple schema roots have the same base, don't
+    // inject it more than once.
+
+    if (!context.injectedRoots.has(this)) {
+      context.injectedRoots.add(this);
+      if (this.base) {
+        this.base.injectInto(dest, context);
+      }
+      super.injectInto(dest, context);
+    }
+  }
+
+  /**
+   * Normalize `obj` according to the loaded schema for `typeName`.
+   *
+   * @param {object} obj The object to normalize against the schema.
+   * @param {string} typeName The name in the format namespace.propertyname
+   * @param {object} context An implementation of Context. Any validation errors
+   *     are reported to the given context.
+   * @returns {object} The normalized object.
+   */
+  normalize(obj, typeName, context) {
+    let [namespaceName, prop] = typeName.split(".");
+    let ns = this.getNamespace(namespaceName);
+    let type = ns.get(prop);
+
+    let result = type.normalize(obj, new Context(context));
+    if (result.error) {
+      return { error: forceString(result.error) };
+    }
+    return result;
+  }
+}
+
+export var Schemas = {
+  initialized: false,
+
+  REVOKE: Symbol("@@revoke"),
+
+  // Maps a schema URL to the JSON contained in that schema file. This
+  // is useful for sending the JSON across processes.
+  schemaJSON: new Map(),
+
+  // A map of schema JSON which should be available in all content processes.
+  contentSchemaJSON: new Map(),
+
+  // A map of schema JSON which should only be available to extension processes.
+  privilegedSchemaJSON: new Map(),
+
+  _rootSchema: null,
+
+  // A weakmap for the validation Context class instances given an extension
+  // context (keyed by the extensin context instance).
+  // This is used instead of the InjectionContext for webIDL API validation
+  // and normalization (see Schemas.checkParameters).
+  paramsValidationContexts: new DefaultWeakMap(
+    extContext => new Context(extContext)
+  ),
+
+  get rootSchema() {
+    if (!this.initialized) {
+      this.init();
+    }
+    if (!this._rootSchema) {
+      this._rootSchema = new SchemaRoot(null, this.schemaJSON);
+      this._rootSchema.parseSchemas();
+    }
+    return this._rootSchema;
+  },
+
+  getNamespace(name) {
+    return this.rootSchema.getNamespace(name);
+  },
+
+  init() {
+    if (this.initialized) {
+      return;
+    }
+    this.initialized = true;
+
+    if (Services.appinfo.processType == Services.appinfo.PROCESS_TYPE_CONTENT) {
+      let addSchemas = schemas => {
+        for (let [key, value] of schemas.entries()) {
+          this.schemaJSON.set(key, value);
+        }
+      };
+
+      if (WebExtensionPolicy.isExtensionProcess || DEBUG) {
+        addSchemas(Services.cpmm.sharedData.get(KEY_PRIVILEGED_SCHEMAS));
+      }
+
+      let schemas = Services.cpmm.sharedData.get(KEY_CONTENT_SCHEMAS);
+      if (schemas) {
+        addSchemas(schemas);
+      }
+    }
+  },
+
+  _loadCachedSchemasPromise: null,
+  loadCachedSchemas() {
+    if (!this._loadCachedSchemasPromise) {
+      this._loadCachedSchemasPromise = lazy.StartupCache.schemas
+        .getAll()
+        .then(results => {
+          return results;
+        });
+    }
+
+    return this._loadCachedSchemasPromise;
+  },
+
+  addSchema(url, schema, content = false) {
+    this.schemaJSON.set(url, schema);
+
+    if (content) {
+      this.contentSchemaJSON.set(url, schema);
+    } else {
+      this.privilegedSchemaJSON.set(url, schema);
+    }
+
+    if (this._rootSchema) {
+      throw new Error("Schema loaded after root schema populated");
+    }
+  },
+
+  updateSharedSchemas() {
+    let { sharedData } = Services.ppmm;
+
+    sharedData.set(KEY_CONTENT_SCHEMAS, this.contentSchemaJSON);
+    sharedData.set(KEY_PRIVILEGED_SCHEMAS, this.privilegedSchemaJSON);
+  },
+
+  fetch(url) {
+    return readJSONAndBlobbify(url);
+  },
+
+  processSchema(json) {
+    return blobbify(json);
+  },
+
+  async load(url, content = false) {
+    if (!isParentProcess) {
+      return;
+    }
+
+    const startTime = Cu.now();
+    let schemaCache = await this.loadCachedSchemas();
+    const fromCache = schemaCache.has(url);
+
+    let blob =
+      schemaCache.get(url) ||
+      (await lazy.StartupCache.schemas.get(url, readJSONAndBlobbify));
+
+    if (!this.schemaJSON.has(url)) {
+      this.addSchema(url, blob, content);
+    }
+
+    ChromeUtils.addProfilerMarker(
+      "ExtensionSchemas",
+      { startTime },
+      `load ${url}, from cache: ${fromCache}`
+    );
+  },
+
+  /**
+   * Checks whether a given object has the necessary permissions to
+   * expose the given namespace.
+   *
+   * @param {string} namespace
+   *        The top-level namespace to check permissions for.
+   * @param {object} wrapperFuncs
+   *        Wrapper functions for the given context.
+   * @param {Function} wrapperFuncs.hasPermission
+   *        A function which, when given a string argument, returns true
+   *        if the context has the given permission.
+   * @returns {boolean}
+   *        True if the context has permission for the given namespace.
+   */
+  checkPermissions(namespace, wrapperFuncs) {
+    return this.rootSchema.checkPermissions(namespace, wrapperFuncs);
+  },
+
+  /**
+   * Returns a sorted array of permission names for the given permission types.
+   *
+   * @param {Array} types An array of permission types, defaults to all permissions.
+   * @returns {Array} sorted array of permission names
+   */
+  getPermissionNames(
+    types = [
+      "Permission",
+      "OptionalPermission",
+      "PermissionNoPrompt",
+      "OptionalPermissionNoPrompt",
+      "PermissionPrivileged",
+    ]
+  ) {
+    const ns = this.getNamespace("manifest");
+    let names = [];
+    for (let typeName of types) {
+      for (let choice of ns
+        .get(typeName)
+        .choices.filter(choice => choice.enumeration)) {
+        names = names.concat(choice.enumeration);
+      }
+    }
+    return names.sort();
+  },
+
+  exportLazyGetter,
+
+  /**
+   * Inject registered extension APIs into `dest`.
+   *
+   * @param {object} dest The root namespace for the APIs.
+   *     This object is usually exposed to extensions as "chrome" or "browser".
+   * @param {object} wrapperFuncs An implementation of the InjectionContext
+   *     interface, which runs the actual functionality of the generated API.
+   */
+  inject(dest, wrapperFuncs) {
+    this.rootSchema.inject(dest, wrapperFuncs);
+  },
+
+  /**
+   * Normalize `obj` according to the loaded schema for `typeName`.
+   *
+   * @param {object} obj The object to normalize against the schema.
+   * @param {string} typeName The name in the format namespace.propertyname
+   * @param {object} context An implementation of Context. Any validation errors
+   *     are reported to the given context.
+   * @returns {object} The normalized object.
+   */
+  normalize(obj, typeName, context) {
+    return this.rootSchema.normalize(obj, typeName, context);
+  },
+
+  /**
+   * Validate and normalize the arguments for an API request originated
+   * from the webIDL API bindings.
+   *
+   * This provides for calls originating through WebIDL the parameters
+   * validation and normalization guarantees that the ext-APINAMESPACE.js
+   * scripts expects (what InjectionContext does for the regular bindings).
+   *
+   * @param {object}                   extContext
+   * @param {mozIExtensionAPIRequest } apiRequest
+   *
+   * @returns {Array<any>} Normalized arguments array.
+   */
+  checkWebIDLRequestParameters(extContext, apiRequest) {
+    const getSchemaForProperty = (schemaObj, propName, schemaPath) => {
+      if (schemaObj instanceof Namespace) {
+        return schemaObj?.get(propName);
+      } else if (schemaObj instanceof SubModuleProperty) {
+        for (const fun of schemaObj.targetType.functions) {
+          if (fun.name === propName) {
+            return fun;
+          }
+        }
+
+        for (const fun of schemaObj.targetType.events) {
+          if (fun.name === propName) {
+            return fun;
+          }
+        }
+      } else if (schemaObj instanceof Event) {
+        return schemaObj;
+      }
+
+      const schemaPathType = schemaObj?.constructor.name;
+      throw new Error(
+        `API Schema for "${propName}" not found in ${schemaPath} (${schemaPath} type is ${schemaPathType})`
+      );
+    };
+    const { requestType, apiNamespace, apiName } = apiRequest;
+
+    let [ns, ...rest] = (
+      ["addListener", "removeListener"].includes(requestType)
+        ? `${apiNamespace}.${apiName}.${requestType}`
+        : `${apiNamespace}.${apiName}`
+    ).split(".");
+    let apiSchema = this.getNamespace(ns);
+
+    // Keep track of the current schema path, populated while navigating the nested API schema
+    // data and then used to include the full path to the API schema that is hitting unexpected
+    // errors due to schema data not found or an unexpected schema type.
+    let schemaPath = [ns];
+
+    while (rest.length) {
+      // Nested property as namespace (e.g. used for proxy.settings requests).
+      if (!apiSchema) {
+        throw new Error(`API Schema not found for ${schemaPath.join(".")}`);
+      }
+
+      let [propName, ...newRest] = rest;
+      rest = newRest;
+
+      apiSchema = getSchemaForProperty(
+        apiSchema,
+        propName,
+        schemaPath.join(".")
+      );
+      schemaPath.push(propName);
+    }
+
+    if (!apiSchema) {
+      throw new Error(`API Schema not found for ${schemaPath.join(".")}`);
+    }
+
+    if (!apiSchema.checkParameters) {
+      throw new Error(
+        `Unexpected API Schema type for ${schemaPath.join(
+          "."
+        )} (${schemaPath.join(".")} type is ${apiSchema.constructor.name})`
+      );
+    }
+
+    return apiSchema.checkParameters(
+      apiRequest.args,
+      this.paramsValidationContexts.get(extContext)
+    );
+  },
+};