--- a/remote/ContentProcessSession.jsm
+++ b/remote/ContentProcessSession.jsm
@@ -1,26 +1,27 @@
 /* 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/. */
 
 "use strict";
 
 var EXPORTED_SYMBOLS = ["ContentProcessSession"];
 
-const {Domains} = ChromeUtils.import("chrome://remote/content/Domains.jsm");
+const {Domains} = ChromeUtils.import("chrome://remote/content/domains/Domains.jsm");
+const {ContentProcessDomains} = ChromeUtils.import("chrome://remote/content/domains/ContentProcessDomains.jsm");
 
 class ContentProcessSession {
   constructor(messageManager, browsingContext, content, docShell) {
     this.messageManager = messageManager;
     this.browsingContext = browsingContext;
     this.content = content;
     this.docShell = docShell;
 
-    this.domains = new Domains(this);
+    this.domains = new Domains(this, ContentProcessDomains);
     this.messageManager.addMessageListener("remote-protocol:request", this);
     this.messageManager.addMessageListener("remote-protocol:destroy", this);
 
     this.destroy = this.destroy.bind(this);
     this.content.addEventListener("unload", this.destroy);
   }
 
   destroy() {

deleted file mode 100644
--- a/remote/Domain.jsm
+++ /dev/null
@@ -1,39 +0,0 @@
-/* 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/. */
-
-"use strict";
-
-var EXPORTED_SYMBOLS = ["Domain"];
-
-const {EventEmitter} = ChromeUtils.import("chrome://remote/content/EventEmitter.jsm");
-const {XPCOMUtils} = ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
-
-class Domain {
-  constructor(session, target) {
-    this.session = session;
-    this.target = target;
-    this.name = this.constructor.name;
-
-    EventEmitter.decorate(this);
-  }
-
-  destructor() {}
-
-  get content() {
-    return this.session.content;
-  }
-
-  get docShell() {
-    return this.session.docShell;
-  }
-
-  get chromeEventHandler() {
-    return this.docShell.chromeEventHandler;
-  }
-}
-
-XPCOMUtils.defineLazyModuleGetters(Domain, {
-  Log: "chrome://remote/content/domain/Log.jsm",
-  Page: "chrome://remote/content/domain/Page.jsm",
-});

deleted file mode 100644
--- a/remote/Domains.jsm
+++ /dev/null
@@ -1,56 +0,0 @@
-/* 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/. */
-
-"use strict";
-
-var EXPORTED_SYMBOLS = ["Domains"];
-
-const {Domain} = ChromeUtils.import("chrome://remote/content/Domain.jsm");
-
-class Domains extends Map {
-  constructor(session) {
-    super();
-    this.session = session;
-  }
-
-  get(name) {
-    let inst = super.get(name);
-    if (!inst) {
-      inst = this.new(name);
-      this.set(inst);
-    }
-    return inst;
-  }
-
-  set(domain) {
-    super.set(domain.name, domain);
-  }
-
-  new(name) {
-    const Cls = Domain[name];
-    if (!Cls) {
-      throw new Error("No such domain: " + name);
-    }
-
-    const inst = new Cls(this.session, this.session.target);
-    inst.on("*", this.session);
-
-    return inst;
-  }
-
-  delete(name) {
-    const inst = super.get(name);
-    if (inst) {
-      inst.off("*");
-      inst.destructor();
-      super.delete(inst.name);
-    }
-  }
-
-  clear() {
-    for (const domainName of this.keys()) {
-      this.delete(domainName);
-    }
-  }
-}

--- a/remote/Session.jsm
+++ b/remote/Session.jsm
@@ -1,32 +1,35 @@
 /* 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/. */
 
 "use strict";
 
 var EXPORTED_SYMBOLS = ["Session"];
 
-const {Domain} = ChromeUtils.import("chrome://remote/content/Domain.jsm");
+const {ParentProcessDomains} = ChromeUtils.import("chrome://remote/content/domains/ParentProcessDomains.jsm");
+const {Domains} = ChromeUtils.import("chrome://remote/content/domains/Domains.jsm");
 const {formatError} = ChromeUtils.import("chrome://remote/content/Error.jsm");
 
 class Session {
   constructor(connection, target) {
     this.connection = connection;
     this.target = target;
 
     this.browsingContext = target.browser.browsingContext;
     this.messageManager = target.browser.messageManager;
     this.messageManager.loadFrameScript("chrome://remote/content/frame-script.js", false);
     this.messageManager.addMessageListener("remote-protocol:event", this);
     this.messageManager.addMessageListener("remote-protocol:result", this);
     this.messageManager.addMessageListener("remote-protocol:error", this);
 
     this.connection.onmessage = this.dispatch.bind(this);
+
+    this.domains = new Domains(this, ParentProcessDomains);
   }
 
   destructor() {
     this.connection.onmessage = null;
 
     this.messageManager.sendAsyncMessage("remote-protocol:destroy", {
       browsingContextId: this.browsingContext.id,
     });
@@ -40,25 +43,31 @@ class Session {
       if (typeof id == "undefined") {
         throw new TypeError("Message missing 'id' field");
       }
       if (typeof method == "undefined") {
         throw new TypeError("Message missing 'method' field");
       }
 
       const [domainName, methodName] = split(method, ".", 1);
-      const domain = Domain[domainName];
-      if (!domain) {
-        throw new TypeError("No such domain: " + domainName);
-      }
+      if (this.domains.domainSupportsMethod(domainName, methodName)) {
+        const inst = this.domains.get(domainName);
+        const methodFn = inst[methodName];
+        if (!methodFn || typeof methodFn != "function") {
+          throw new Error(`Method implementation of ${methodName} missing`);
+        }
 
-      this.messageManager.sendAsyncMessage("remote-protocol:request", {
-        browsingContextId: this.browsingContext.id,
-        request: {id, domainName, methodName, params},
-      });
+        const result = await methodFn.call(inst, params);
+        this.connection.send({id, result});
+      } else {
+        this.messageManager.sendAsyncMessage("remote-protocol:request", {
+          browsingContextId: this.browsingContext.id,
+          request: {id, domainName, methodName, params},
+        });
+      }
     } catch (e) {
       const error = formatError(e, {stack: true});
       this.connection.send({id, error});
     }
   }
 
   receiveMessage({name, data}) {
     const {id, result, event, error} = data;
@@ -72,16 +81,23 @@ class Session {
       this.connection.send(event);
       break;
 
     case "remote-protocol:error":
       this.connection.send({id, error: formatError(error, {stack: true})});
       break;
     }
   }
+
+  onevent(eventName, params) {
+    this.connection.send({
+      method: eventName,
+      params,
+    });
+  }
 }
 
 /**
  * Split s by sep, returning list of substrings.
  * If max is given, at most max splits are done.
  * If max is 0, there is no limit on the number of splits.
  */
 function split(s, sep, max = 0) {

deleted file mode 100644
--- a/remote/domain/Log.jsm
+++ /dev/null
@@ -1,136 +0,0 @@
-/* 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/. */
-
-"use strict";
-
-var EXPORTED_SYMBOLS = ["Log"];
-
-const {Domain} = ChromeUtils.import("chrome://remote/content/Domain.jsm");
-const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
-
-class Log extends Domain {
-  constructor(session, target) {
-    super(session, target);
-    this.enabled = false;
-  }
-
-  destructor() {
-    this.disable();
-  }
-
-  enable() {
-    if (!this.enabled) {
-      this.enabled = true;
-
-      Services.console.registerListener(this);
-      Services.obs.addObserver(this, "console-api-log-event");
-    }
-  }
-
-  disable() {
-    if (this.enabled) {
-      this.enabled = false;
-      Services.console.unregisterListener(this);
-      Services.obs.removeObserver(this, "console-api-log-event");
-    }
-  }
-
-  // nsIObserver
-
-  /**
-   * Takes all script error messages belonging to the current window
-   * and emits a "console-service-message" event.
-   *
-   * @param {nsIConsoleMessage} message
-   *     Message originating from the nsIConsoleService.
-   */
-  observe(message, topic) {
-    let entry;
-    if (message instanceof Ci.nsIScriptError) {
-      entry = fromScriptError(message);
-    } else if (message instanceof Ci.nsIConsoleMessage) {
-      entry = fromConsoleMessage(message);
-    } else if (topic == "console-api-log-event") {
-      entry = fromConsoleAPI(message.wrappedJSObject);
-    }
-
-    this.emit("Log.entryAdded", {entry});
-  }
-
-  // XPCOM
-
-  get QueryInterface() {
-    return ChromeUtils.generateQI([Ci.nsIConsoleListener]);
-  }
-}
-
-function fromConsoleMessage(message) {
-  const levels = {
-    [Ci.nsIConsoleMessage.debug]: "verbose",
-    [Ci.nsIConsoleMessage.info]: "info",
-    [Ci.nsIConsoleMessage.warn]: "warning",
-    [Ci.nsIConsoleMessage.error]: "error",
-  };
-  const level = levels[message.logLevel];
-
-  return {
-    source: "javascript",
-    level,
-    text: message.message,
-    timestamp: Date.now(),
-  };
-}
-
-function fromConsoleAPI(message) {
-  // message is a ConsoleEvent instance:
-  // https://searchfox.org/mozilla-central/rev/00c0d068ece99717bea7475f7dc07e61f7f35984/dom/webidl/Console.webidl#83-107
-
-  // A couple of possible level are defined here:
-  // https://searchfox.org/mozilla-central/rev/00c0d068ece99717bea7475f7dc07e61f7f35984/dom/console/Console.cpp#1086-1100
-  const levels = {
-    "log": "verbose",
-    "info": "info",
-    "warn": "warning",
-    "error": "error",
-    "exception": "error",
-
-  };
-  const level = levels[message.level] || "info";
-
-  return {
-    source: "javascript",
-    level,
-    text: message.arguments,
-    url: message.filename,
-    lineNumber: message.lineNumber,
-    stackTrace: message.stacktrace,
-    timestamp: Date.now(),
-  };
-}
-
-function fromScriptError(error) {
-  const {flags, errorMessage, sourceName, lineNumber, stack} = error;
-
-  // lossy reduction from bitmask to CDP string level
-  let level = "verbose";
-  if ((flags & Ci.nsIScriptError.exceptionFlag) ||
-      (flags & Ci.nsIScriptError.errorFlag)) {
-    level = "error";
-  } else if ((flags & Ci.nsIScriptError.warningFlag) ||
-      (flags & Ci.nsIScriptError.strictFlag)) {
-    level = "warning";
-  } else if (flags & Ci.nsIScriptError.infoFlag) {
-    level = "info";
-  }
-
-  return {
-    source: "javascript",
-    level,
-    text: errorMessage,
-    timestamp: Date.now(),
-    url: sourceName,
-    lineNumber,
-    stackTrace: stack,
-  };
-}

deleted file mode 100644
--- a/remote/domain/Page.jsm
+++ /dev/null
@@ -1,97 +0,0 @@
-/* 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/. */
-
-"use strict";
-
-var EXPORTED_SYMBOLS = ["Page"];
-
-const {Domain} = ChromeUtils.import("chrome://remote/content/Domain.jsm");
-const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
-const {UnsupportedError} = ChromeUtils.import("chrome://remote/content/Error.jsm");
-
-class Page extends Domain {
-  constructor(session, target) {
-    super(session, target);
-    this.enabled = false;
-  }
-
-  destructor() {
-    this.disable();
-  }
-
-  QueryInterface(iid) {
-    if (iid.equals(Ci.nsIWebProgressListener) ||
-      iid.equals(Ci.nsISupportsWeakReference) ||
-      iid.equals(Ci.nsIObserver)) {
-      return this;
-    }
-    throw Cr.NS_ERROR_NO_INTERFACE;
-  }
-
-  // commands
-
-  async enable() {
-    if (!this.enabled) {
-      this.enabled = true;
-      this.chromeEventHandler.addEventListener("DOMContentLoaded", this,
-        {mozSystemGroup: true});
-      this.chromeEventHandler.addEventListener("pageshow", this,
-        {mozSystemGroup: true});
-    }
-  }
-
-  disable() {
-    if (this.enabled) {
-      this.chromeEventHandler.removeEventListener("DOMContentLoaded", this,
-        {mozSystemGroup: true});
-      this.chromeEventHandler.removeEventListener("pageshow", this,
-        {mozSystemGroup: true});
-      this.enabled = false;
-    }
-  }
-
-  async navigate({url, referrer, transitionType, frameId} = {}) {
-    if (frameId) {
-      throw new UnsupportedError("frameId not supported");
-    }
-
-    const opts = {
-      loadFlags: transitionToLoadFlag(transitionType),
-      referrerURI: referrer,
-      triggeringPrincipal: Services.scriptSecurityManager.getSystemPrincipal(),
-    };
-    this.docShell.QueryInterface(Ci.nsIWebNavigation);
-    this.docShell.loadURI(url, opts);
-
-    return {frameId: "42"};
-  }
-
-  url() {
-    return this.content.location.href;
-  }
-
-  handleEvent({type}) {
-    const timestamp = Date.now();
-
-    switch (type) {
-    case "DOMContentLoaded":
-      this.emit("Page.domContentEventFired", {timestamp});
-      break;
-
-    case "pageshow":
-      this.emit("Page.loadEventFired", {timestamp});
-      break;
-    }
-  }
-}
-
-function transitionToLoadFlag(transitionType) {
-  switch (transitionType) {
-  case "reload":
-    return Ci.nsIWebNavigation.LOAD_FLAG_IS_REFRESH;
-  case "link":
-  default:
-    return Ci.nsIWebNavigation.LOAD_FLAG_IS_LINK;
-  }
-}

new file mode 100644
--- /dev/null
+++ b/remote/domains/ContentProcessDomains.jsm
@@ -0,0 +1,16 @@
+/* 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/. */
+
+"use strict";
+
+var EXPORTED_SYMBOLS = ["ContentProcessDomains"];
+
+const {XPCOMUtils} = ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
+
+const ContentProcessDomains = {};
+
+XPCOMUtils.defineLazyModuleGetters(ContentProcessDomains, {
+  Log: "chrome://remote/content/domains/content/Log.jsm",
+  Page: "chrome://remote/content/domains/content/Page.jsm",
+});

new file mode 100644
--- /dev/null
+++ b/remote/domains/Domain.jsm
@@ -0,0 +1,33 @@
+/* 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/. */
+
+"use strict";
+
+var EXPORTED_SYMBOLS = ["Domain"];
+
+const {EventEmitter} = ChromeUtils.import("chrome://remote/content/EventEmitter.jsm");
+
+class Domain {
+  constructor(session, target) {
+    this.session = session;
+    this.target = target;
+    this.name = this.constructor.name;
+
+    EventEmitter.decorate(this);
+  }
+
+  destructor() {}
+
+  get content() {
+    return this.session.content;
+  }
+
+  get docShell() {
+    return this.session.docShell;
+  }
+
+  get chromeEventHandler() {
+    return this.docShell.chromeEventHandler;
+  }
+}

new file mode 100644
--- /dev/null
+++ b/remote/domains/Domains.jsm
@@ -0,0 +1,60 @@
+/* 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/. */
+
+"use strict";
+
+var EXPORTED_SYMBOLS = ["Domains"];
+
+class Domains extends Map {
+  constructor(session, modules) {
+    super();
+    this.session = session;
+    this.modules = modules;
+  }
+
+  domainSupportsMethod(name, method) {
+    const domain = this.modules[name];
+    return domain && !!domain.prototype[method];
+  }
+
+  get(name) {
+    let inst = super.get(name);
+    if (!inst) {
+      inst = this.new(name);
+      this.set(inst);
+    }
+    return inst;
+  }
+
+  set(domain) {
+    super.set(domain.name, domain);
+  }
+
+  new(name) {
+    const Cls = this.modules[name];
+    if (!Cls) {
+      throw new Error("No such domain: " + name);
+    }
+
+    const inst = new Cls(this.session, this.session.target);
+    inst.on("*", this.session);
+
+    return inst;
+  }
+
+  delete(name) {
+    const inst = super.get(name);
+    if (inst) {
+      inst.off("*");
+      inst.destructor();
+      super.delete(inst.name);
+    }
+  }
+
+  clear() {
+    for (const domainName of this.keys()) {
+      this.delete(domainName);
+    }
+  }
+}

new file mode 100644
--- /dev/null
+++ b/remote/domains/ParentProcessDomains.jsm
@@ -0,0 +1,15 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+var EXPORTED_SYMBOLS = ["ParentProcessDomains"];
+
+const {XPCOMUtils} = ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
+
+const ParentProcessDomains = {};
+
+XPCOMUtils.defineLazyModuleGetters(ParentProcessDomains, {
+  Browser: "chrome://remote/content/domains/parent/Browser.jsm",
+});

new file mode 100644
--- /dev/null
+++ b/remote/domains/content/Log.jsm
@@ -0,0 +1,136 @@
+/* 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/. */
+
+"use strict";
+
+var EXPORTED_SYMBOLS = ["Log"];
+
+const {Domain} = ChromeUtils.import("chrome://remote/content/domains/Domain.jsm");
+const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+class Log extends Domain {
+  constructor(session, target) {
+    super(session, target);
+    this.enabled = false;
+  }
+
+  destructor() {
+    this.disable();
+  }
+
+  enable() {
+    if (!this.enabled) {
+      this.enabled = true;
+
+      Services.console.registerListener(this);
+      Services.obs.addObserver(this, "console-api-log-event");
+    }
+  }
+
+  disable() {
+    if (this.enabled) {
+      this.enabled = false;
+      Services.console.unregisterListener(this);
+      Services.obs.removeObserver(this, "console-api-log-event");
+    }
+  }
+
+  // nsIObserver
+
+  /**
+   * Takes all script error messages belonging to the current window
+   * and emits a "console-service-message" event.
+   *
+   * @param {nsIConsoleMessage} message
+   *     Message originating from the nsIConsoleService.
+   */
+  observe(message, topic) {
+    let entry;
+    if (message instanceof Ci.nsIScriptError) {
+      entry = fromScriptError(message);
+    } else if (message instanceof Ci.nsIConsoleMessage) {
+      entry = fromConsoleMessage(message);
+    } else if (topic == "console-api-log-event") {
+      entry = fromConsoleAPI(message.wrappedJSObject);
+    }
+
+    this.emit("Log.entryAdded", {entry});
+  }
+
+  // XPCOM
+
+  get QueryInterface() {
+    return ChromeUtils.generateQI([Ci.nsIConsoleListener]);
+  }
+}
+
+function fromConsoleMessage(message) {
+  const levels = {
+    [Ci.nsIConsoleMessage.debug]: "verbose",
+    [Ci.nsIConsoleMessage.info]: "info",
+    [Ci.nsIConsoleMessage.warn]: "warning",
+    [Ci.nsIConsoleMessage.error]: "error",
+  };
+  const level = levels[message.logLevel];
+
+  return {
+    source: "javascript",
+    level,
+    text: message.message,
+    timestamp: Date.now(),
+  };
+}
+
+function fromConsoleAPI(message) {
+  // message is a ConsoleEvent instance:
+  // https://searchfox.org/mozilla-central/rev/00c0d068ece99717bea7475f7dc07e61f7f35984/dom/webidl/Console.webidl#83-107
+
+  // A couple of possible level are defined here:
+  // https://searchfox.org/mozilla-central/rev/00c0d068ece99717bea7475f7dc07e61f7f35984/dom/console/Console.cpp#1086-1100
+  const levels = {
+    "log": "verbose",
+    "info": "info",
+    "warn": "warning",
+    "error": "error",
+    "exception": "error",
+
+  };
+  const level = levels[message.level] || "info";
+
+  return {
+    source: "javascript",
+    level,
+    text: message.arguments,
+    url: message.filename,
+    lineNumber: message.lineNumber,
+    stackTrace: message.stacktrace,
+    timestamp: Date.now(),
+  };
+}
+
+function fromScriptError(error) {
+  const {flags, errorMessage, sourceName, lineNumber, stack} = error;
+
+  // lossy reduction from bitmask to CDP string level
+  let level = "verbose";
+  if ((flags & Ci.nsIScriptError.exceptionFlag) ||
+      (flags & Ci.nsIScriptError.errorFlag)) {
+    level = "error";
+  } else if ((flags & Ci.nsIScriptError.warningFlag) ||
+      (flags & Ci.nsIScriptError.strictFlag)) {
+    level = "warning";
+  } else if (flags & Ci.nsIScriptError.infoFlag) {
+    level = "info";
+  }
+
+  return {
+    source: "javascript",
+    level,
+    text: errorMessage,
+    timestamp: Date.now(),
+    url: sourceName,
+    lineNumber,
+    stackTrace: stack,
+  };
+}

new file mode 100644
--- /dev/null
+++ b/remote/domains/content/Page.jsm
@@ -0,0 +1,97 @@
+/* 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/. */
+
+"use strict";
+
+var EXPORTED_SYMBOLS = ["Page"];
+
+const {Domain} = ChromeUtils.import("chrome://remote/content/domains/Domain.jsm");
+const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
+const {UnsupportedError} = ChromeUtils.import("chrome://remote/content/Error.jsm");
+
+class Page extends Domain {
+  constructor(session, target) {
+    super(session, target);
+    this.enabled = false;
+  }
+
+  destructor() {
+    this.disable();
+  }
+
+  QueryInterface(iid) {
+    if (iid.equals(Ci.nsIWebProgressListener) ||
+      iid.equals(Ci.nsISupportsWeakReference) ||
+      iid.equals(Ci.nsIObserver)) {
+      return this;
+    }
+    throw Cr.NS_ERROR_NO_INTERFACE;
+  }
+
+  // commands
+
+  async enable() {
+    if (!this.enabled) {
+      this.enabled = true;
+      this.chromeEventHandler.addEventListener("DOMContentLoaded", this,
+        {mozSystemGroup: true});
+      this.chromeEventHandler.addEventListener("pageshow", this,
+        {mozSystemGroup: true});
+    }
+  }
+
+  disable() {
+    if (this.enabled) {
+      this.chromeEventHandler.removeEventListener("DOMContentLoaded", this,
+        {mozSystemGroup: true});
+      this.chromeEventHandler.removeEventListener("pageshow", this,
+        {mozSystemGroup: true});
+      this.enabled = false;
+    }
+  }
+
+  async navigate({url, referrer, transitionType, frameId} = {}) {
+    if (frameId) {
+      throw new UnsupportedError("frameId not supported");
+    }
+
+    const opts = {
+      loadFlags: transitionToLoadFlag(transitionType),
+      referrerURI: referrer,
+      triggeringPrincipal: Services.scriptSecurityManager.getSystemPrincipal(),
+    };
+    this.docShell.QueryInterface(Ci.nsIWebNavigation);
+    this.docShell.loadURI(url, opts);
+
+    return {frameId: "42"};
+  }
+
+  url() {
+    return this.content.location.href;
+  }
+
+  handleEvent({type}) {
+    const timestamp = Date.now();
+
+    switch (type) {
+    case "DOMContentLoaded":
+      this.emit("Page.domContentEventFired", {timestamp});
+      break;
+
+    case "pageshow":
+      this.emit("Page.loadEventFired", {timestamp});
+      break;
+    }
+  }
+}
+
+function transitionToLoadFlag(transitionType) {
+  switch (transitionType) {
+  case "reload":
+    return Ci.nsIWebNavigation.LOAD_FLAG_IS_REFRESH;
+  case "link":
+  default:
+    return Ci.nsIWebNavigation.LOAD_FLAG_IS_LINK;
+  }
+}

new file mode 100644
--- /dev/null
+++ b/remote/domains/parent/Browser.jsm
@@ -0,0 +1,28 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+var EXPORTED_SYMBOLS = ["Browser"];
+
+const {Domain} = ChromeUtils.import("chrome://remote/content/domains/Domain.jsm");
+
+class Browser extends Domain {
+  constructor(session, target) {
+    super(session, target);
+  }
+
+  destructor() {
+  }
+
+  getVersion() {
+    return {
+      protocolVersion: "1",
+      product: "Firefox",
+      revision: "1",
+      userAgent: "Firefox",
+      jsVersion: "1.8.5",
+    };
+  }
+}

--- a/remote/jar.mn
+++ b/remote/jar.mn
@@ -1,18 +1,16 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 remote.jar:
 % content remote %content/
   content/Connection.jsm (Connection.jsm)
   content/ContentProcessSession.jsm (ContentProcessSession.jsm)
-  content/Domain.jsm (Domain.jsm)
-  content/Domains.jsm (Domains.jsm)
   content/Error.jsm (Error.jsm)
   content/EventEmitter.jsm (EventEmitter.jsm)
   content/Handler.jsm (Handler.jsm)
   content/Log.jsm (Log.jsm)
   content/Observer.jsm (Observer.jsm)
   content/Prefs.jsm (Prefs.jsm)
   content/Protocol.jsm (Protocol.jsm)
   content/Session.jsm (Session.jsm)
@@ -21,18 +19,23 @@ remote.jar:
   content/TargetListener.jsm (TargetListener.jsm)
   content/Targets.jsm (Targets.jsm)
   content/WindowManager.jsm (WindowManager.jsm)
 
   # Frame scripts
   content/frame-script.js (frame-script.js)
 
   # domains
-  content/domain/Log.jsm (domain/Log.jsm)
-  content/domain/Page.jsm (domain/Page.jsm)
+  content/domains/Domain.jsm (domains/Domain.jsm)
+  content/domains/Domains.jsm (domains/Domains.jsm)
+  content/domains/ContentProcessDomains.jsm (domains/ContentProcessDomains.jsm)
+  content/domains/ParentProcessDomains.jsm (domains/ParentProcessDomains.jsm)
+  content/domains/content/Log.jsm (domains/content/Log.jsm)
+  content/domains/content/Page.jsm (domains/content/Page.jsm)
+  content/domains/parent/Browser.jsm (domains/parent/Browser.jsm)
 
   # transport layer
   content/server/HTTPD.jsm (../netwerk/test/httpserver/httpd.js)
   content/server/Packet.jsm (server/Packet.jsm)
   content/server/Socket.jsm (server/Socket.jsm)
   content/server/Stream.jsm (server/Stream.jsm)
   content/server/Transport.jsm (server/Transport.jsm)
   content/server/WebSocket.jsm (server/WebSocket.jsm)

--- a/remote/test/browser/browser_cdp.js
+++ b/remote/test/browser/browser_cdp.js
@@ -41,20 +41,24 @@ async function testCDP() {
       // Ensure debugging the right target, i.e. the one for our test tab.
       return list.find(target => {
         return target.url == TEST_URI;
       });
     },
   });
   ok(true, "CDP client has been instantiated");
 
-  const {Log, Page} = client;
+  const {Browser, Log, Page} = client;
+  ok("Browser" in client, "Browser domain is available");
   ok("Log" in client, "Log domain is available");
   ok("Page" in client, "Page domain is available");
 
+  const version = await Browser.getVersion();
+  is(version.product, "Firefox", "Browser.getVersion works");
+
   // receive console.log messages and print them
   Log.enable();
   ok(true, "Log domain has been enabled");
 
   Log.entryAdded(({entry}) => {
     const {timestamp, level, text, args} = entry;
     const msg = text || args.join(" ");
     console.log(`${new Date(timestamp)}\t${level.toUpperCase()}\t${msg}`);