Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

18 files changed, 3349 insertions, 0 deletions

diff --git a/devtools/server/actors/targets/base-target-actor.js b/devtools/server/actors/targets/base-target-actor.js
new file mode 100644
index 0000000000..2108e74a0f
--- /dev/null
+++ b/devtools/server/actors/targets/base-target-actor.js
@@ -0,0 +1,114 @@
+/* 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";
+
+const { Actor } = require("resource://devtools/shared/protocol.js");
+
+loader.lazyRequireGetter(
+  this,
+  "SessionDataProcessors",
+  "resource://devtools/server/actors/targets/session-data-processors/index.js",
+  true
+);
+
+class BaseTargetActor extends Actor {
+  constructor(conn, targetType, spec) {
+    super(conn, spec);
+
+    /**
+     * Type of target, a string of Targets.TYPES.
+     * @return {string}
+     */
+    this.targetType = targetType;
+  }
+
+  /**
+   * Process a new data entry, which can be watched resources, breakpoints, ...
+   *
+   * @param string type
+   *        The type of data to be added
+   * @param Array<Object> entries
+   *        The values to be added to this type of data
+   * @param Boolean isDocumentCreation
+   *        Set to true if this function is called just after a new document (and its
+   *        associated target) is created.
+   */
+  async addSessionDataEntry(type, entries, isDocumentCreation = false) {
+    const processor = SessionDataProcessors[type];
+    if (processor) {
+      await processor.addSessionDataEntry(this, entries, isDocumentCreation);
+    }
+  }
+
+  /**
+   * Remove data entries that have been previously added via addSessionDataEntry
+   *
+   * See addSessionDataEntry for argument description.
+   */
+  removeSessionDataEntry(type, entries) {
+    const processor = SessionDataProcessors[type];
+    if (processor) {
+      processor.removeSessionDataEntry(this, entries);
+    }
+  }
+
+  /**
+   * Called by Resource Watchers, when new resources are available, updated or destroyed.
+   *
+   * @param String updateType
+   *        Can be "available", "updated" or "destroyed"
+   * @param Array<json> resources
+   *        List of all resource's form. A resource is a JSON object piped over to the client.
+   *        It can contain actor IDs, actor forms, to be manually marshalled by the client.
+   */
+  notifyResources(updateType, resources) {
+    if (resources.length === 0 || this.isDestroyed()) {
+      // Don't try to emit if the resources array is empty or the actor was
+      // destroyed.
+      return;
+    }
+
+    if (this.devtoolsSpawnedBrowsingContextForWebExtension) {
+      this.overrideResourceBrowsingContextForWebExtension(resources);
+    }
+
+    this.emit(`resource-${updateType}-form`, resources);
+  }
+
+  /**
+   * For WebExtension, we have to hack all resource's browsingContextID
+   * in order to ensure emitting them with the fixed, original browsingContextID
+   * related to the fallback document created by devtools which always exists.
+   * The target's form will always be relating to that BrowsingContext IDs (browsing context ID and inner window id).
+   * Even if the target switches internally to another document via WindowGlobalTargetActor._setWindow.
+   *
+   * @param {Array<Objects>} List of resources
+   */
+  overrideResourceBrowsingContextForWebExtension(resources) {
+    const browsingContextID =
+      this.devtoolsSpawnedBrowsingContextForWebExtension.id;
+    resources.forEach(
+      resource => (resource.browsingContextID = browsingContextID)
+    );
+  }
+
+  /**
+   * Try to return any target scoped actor instance, if it exists.
+   * They are lazily instantiated and so will only be available
+   * if the client called at least one of their method.
+   *
+   * @param {String} prefix
+   *        Prefix for the actor we would like to retrieve.
+   *        Defined in devtools/server/actors/utils/actor-registry.js
+   */
+  getTargetScopedActor(prefix) {
+    if (this.isDestroyed()) {
+      return null;
+    }
+    const form = this.form();
+    return this.conn._getOrCreateActor(form[prefix + "Actor"]);
+  }
+}
+exports.BaseTargetActor = BaseTargetActor;
diff --git a/devtools/server/actors/targets/content-process.js b/devtools/server/actors/targets/content-process.js
new file mode 100644
index 0000000000..239eae8bc8
--- /dev/null
+++ b/devtools/server/actors/targets/content-process.js
@@ -0,0 +1,264 @@
+/* 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";
+
+/*
+ * Target actor for all resources in a content process of Firefox (chrome sandboxes, frame
+ * scripts, documents, etc.)
+ *
+ * See devtools/docs/backend/actor-hierarchy.md for more details.
+ */
+
+const { ThreadActor } = require("resource://devtools/server/actors/thread.js");
+const {
+  WebConsoleActor,
+} = require("resource://devtools/server/actors/webconsole.js");
+const makeDebugger = require("resource://devtools/server/actors/utils/make-debugger.js");
+const { Pool } = require("resource://devtools/shared/protocol.js");
+const { assert } = require("resource://devtools/shared/DevToolsUtils.js");
+const {
+  SourcesManager,
+} = require("resource://devtools/server/actors/utils/sources-manager.js");
+const {
+  contentProcessTargetSpec,
+} = require("resource://devtools/shared/specs/targets/content-process.js");
+const Targets = require("resource://devtools/server/actors/targets/index.js");
+const Resources = require("resource://devtools/server/actors/resources/index.js");
+const {
+  BaseTargetActor,
+} = require("resource://devtools/server/actors/targets/base-target-actor.js");
+const { TargetActorRegistry } = ChromeUtils.importESModule(
+  "resource://devtools/server/actors/targets/target-actor-registry.sys.mjs",
+  {
+    loadInDevToolsLoader: false,
+  }
+);
+
+loader.lazyRequireGetter(
+  this,
+  "WorkerDescriptorActorList",
+  "resource://devtools/server/actors/worker/worker-descriptor-actor-list.js",
+  true
+);
+loader.lazyRequireGetter(
+  this,
+  "MemoryActor",
+  "resource://devtools/server/actors/memory.js",
+  true
+);
+loader.lazyRequireGetter(
+  this,
+  "TracerActor",
+  "resource://devtools/server/actors/tracer.js",
+  true
+);
+
+class ContentProcessTargetActor extends BaseTargetActor {
+  constructor(conn, { isXpcShellTarget = false, sessionContext } = {}) {
+    super(conn, Targets.TYPES.PROCESS, contentProcessTargetSpec);
+
+    this.threadActor = null;
+    this.isXpcShellTarget = isXpcShellTarget;
+    this.sessionContext = sessionContext;
+
+    // Use a see-everything debugger
+    this.makeDebugger = makeDebugger.bind(null, {
+      findDebuggees: dbg => dbg.findAllGlobals(),
+      shouldAddNewGlobalAsDebuggee: global => true,
+    });
+
+    const sandboxPrototype = {
+      get tabs() {
+        return Array.from(
+          Services.ww.getWindowEnumerator(),
+          win => win.docShell.messageManager
+        );
+      },
+    };
+
+    // Scope into which the webconsole executes:
+    // A sandbox with chrome privileges with a `tabs` getter.
+    const systemPrincipal = Cc["@mozilla.org/systemprincipal;1"].createInstance(
+      Ci.nsIPrincipal
+    );
+    const sandbox = Cu.Sandbox(systemPrincipal, {
+      sandboxPrototype,
+      wantGlobalProperties: ["ChromeUtils"],
+    });
+    this._consoleScope = sandbox;
+
+    this._workerList = null;
+    this._workerDescriptorActorPool = null;
+    this._onWorkerListChanged = this._onWorkerListChanged.bind(this);
+
+    // Try to destroy the Content Process Target when the content process shuts down.
+    // The parent process can't communicate during shutdown as the communication channel
+    // is already down (message manager or JS Window Actor API).
+    // So that we have to observe to some event fired from this process.
+    // While such cleanup doesn't sound ultimately necessary (the process will be completely destroyed)
+    // mochitests are asserting that there is no leaks during process shutdown.
+    // Do not override destroy as Protocol.js may override it when calling destroy,
+    // and we won't be able to call removeObserver correctly.
+    this.destroyObserver = this.destroy.bind(this);
+    Services.obs.addObserver(this.destroyObserver, "xpcom-shutdown");
+    if (this.isXpcShellTarget) {
+      TargetActorRegistry.registerXpcShellTargetActor(this);
+    }
+  }
+
+  get isRootActor() {
+    return true;
+  }
+
+  get url() {
+    return undefined;
+  }
+
+  get window() {
+    return this._consoleScope;
+  }
+
+  get sourcesManager() {
+    if (!this._sourcesManager) {
+      assert(
+        this.threadActor,
+        "threadActor should exist when creating SourcesManager."
+      );
+      this._sourcesManager = new SourcesManager(this.threadActor);
+    }
+    return this._sourcesManager;
+  }
+
+  /*
+   * Return a Debugger instance or create one if there is none yet
+   */
+  get dbg() {
+    if (!this._dbg) {
+      this._dbg = this.makeDebugger();
+    }
+    return this._dbg;
+  }
+
+  form() {
+    if (!this._consoleActor) {
+      this._consoleActor = new WebConsoleActor(this.conn, this);
+      this.manage(this._consoleActor);
+    }
+
+    if (!this.threadActor) {
+      this.threadActor = new ThreadActor(this, null);
+      this.manage(this.threadActor);
+    }
+    if (!this.memoryActor) {
+      this.memoryActor = new MemoryActor(this.conn, this);
+      this.manage(this.memoryActor);
+    }
+    if (!this.tracerActor) {
+      this.tracerActor = new TracerActor(this.conn, this);
+      this.manage(this.tracerActor);
+    }
+
+    return {
+      actor: this.actorID,
+      isXpcShellTarget: this.isXpcShellTarget,
+      processID: Services.appinfo.processID,
+      remoteType: Services.appinfo.remoteType,
+
+      consoleActor: this._consoleActor.actorID,
+      memoryActor: this.memoryActor.actorID,
+      threadActor: this.threadActor.actorID,
+      tracerActor: this.tracerActor.actorID,
+
+      traits: {
+        networkMonitor: false,
+        // See trait description in browsing-context.js
+        supportsTopLevelTargetFlag: false,
+      },
+    };
+  }
+
+  ensureWorkerList() {
+    if (!this._workerList) {
+      this._workerList = new WorkerDescriptorActorList(this.conn, {});
+    }
+    return this._workerList;
+  }
+
+  listWorkers() {
+    return this.ensureWorkerList()
+      .getList()
+      .then(actors => {
+        const pool = new Pool(this.conn, "workers");
+        for (const actor of actors) {
+          pool.manage(actor);
+        }
+
+        // Do not destroy the pool before transfering ownership to the newly created
+        // pool, so that we do not accidentally destroy actors that are still in use.
+        if (this._workerDescriptorActorPool) {
+          this._workerDescriptorActorPool.destroy();
+        }
+
+        this._workerDescriptorActorPool = pool;
+        this._workerList.onListChanged = this._onWorkerListChanged;
+
+        return { workers: actors };
+      });
+  }
+
+  _onWorkerListChanged() {
+    this.conn.send({ from: this.actorID, type: "workerListChanged" });
+    this._workerList.onListChanged = null;
+  }
+
+  pauseMatchingServiceWorkers(request) {
+    this.ensureWorkerList().workerPauser.setPauseServiceWorkers(request.origin);
+  }
+
+  destroy() {
+    // Avoid reentrancy. We will destroy the Transport when emitting "destroyed",
+    // which will force destroying all actors.
+    if (this.destroying) {
+      return;
+    }
+    this.destroying = true;
+
+    // Unregistering watchers first is important
+    // otherwise you might have leaks reported when running browser_browser_toolbox_netmonitor.js in debug builds
+    Resources.unwatchAllResources(this);
+
+    this.emit("destroyed");
+
+    super.destroy();
+
+    if (this.threadActor) {
+      this.threadActor = null;
+    }
+
+    // Tell the live lists we aren't watching any more.
+    if (this._workerList) {
+      this._workerList.destroy();
+      this._workerList = null;
+    }
+
+    if (this._sourcesManager) {
+      this._sourcesManager.destroy();
+      this._sourcesManager = null;
+    }
+
+    if (this._dbg) {
+      this._dbg.disable();
+      this._dbg = null;
+    }
+
+    Services.obs.removeObserver(this.destroyObserver, "xpcom-shutdown");
+
+    if (this.isXpcShellTarget) {
+      TargetActorRegistry.unregisterXpcShellTargetActor(this);
+    }
+  }
+}
+
+exports.ContentProcessTargetActor = ContentProcessTargetActor;
diff --git a/devtools/server/actors/targets/index.js b/devtools/server/actors/targets/index.js
new file mode 100644
index 0000000000..aced448459
--- /dev/null
+++ b/devtools/server/actors/targets/index.js
@@ -0,0 +1,12 @@
+/* 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";
+
+const TYPES = {
+  FRAME: "frame",
+  PROCESS: "process",
+  WORKER: "worker",
+};
+exports.TYPES = TYPES;
diff --git a/devtools/server/actors/targets/moz.build b/devtools/server/actors/targets/moz.build
new file mode 100644
index 0000000000..f4d44ae669
--- /dev/null
+++ b/devtools/server/actors/targets/moz.build
@@ -0,0 +1,20 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+DIRS += [
+    "session-data-processors",
+]
+
+DevToolsModules(
+    "base-target-actor.js",
+    "content-process.js",
+    "index.js",
+    "parent-process.js",
+    "target-actor-registry.sys.mjs",
+    "webextension.js",
+    "window-global.js",
+    "worker.js",
+)
diff --git a/devtools/server/actors/targets/parent-process.js b/devtools/server/actors/targets/parent-process.js
new file mode 100644
index 0000000000..2170bd0b1e
--- /dev/null
+++ b/devtools/server/actors/targets/parent-process.js
@@ -0,0 +1,166 @@
+/* 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";
+
+/*
+ * Target actor for the entire parent process.
+ *
+ * This actor extends WindowGlobalTargetActor.
+ * This actor is extended by WebExtensionTargetActor.
+ *
+ * See devtools/docs/backend/actor-hierarchy.md for more details.
+ */
+
+const {
+  DevToolsServer,
+} = require("resource://devtools/server/devtools-server.js");
+const {
+  getChildDocShells,
+  WindowGlobalTargetActor,
+} = require("resource://devtools/server/actors/targets/window-global.js");
+const makeDebugger = require("resource://devtools/server/actors/utils/make-debugger.js");
+
+const {
+  parentProcessTargetSpec,
+} = require("resource://devtools/shared/specs/targets/parent-process.js");
+
+class ParentProcessTargetActor extends WindowGlobalTargetActor {
+  /**
+   * Creates a target actor for debugging all the chrome content in the parent process.
+   * Most of the implementation is inherited from WindowGlobalTargetActor.
+   * ParentProcessTargetActor is a child of RootActor, it can be instantiated via
+   * RootActor.getProcess request. ParentProcessTargetActor exposes all target-scoped actors
+   * via its form() request, like WindowGlobalTargetActor.
+   *
+   * @param conn DevToolsServerConnection
+   *        The connection to the client.
+   * @param {Object} options
+   *        - isTopLevelTarget: {Boolean} flag to indicate if this is the top
+   *          level target of the DevTools session
+   *        - sessionContext Object
+   *          The Session Context to help know what is debugged.
+   *          See devtools/server/actors/watcher/session-context.js
+   *        - customSpec Object
+   *          WebExtensionTargetActor inherits from ParentProcessTargetActor
+   *          and has to use its own protocol.js specification object.
+   */
+  constructor(
+    conn,
+    { isTopLevelTarget, sessionContext, customSpec = parentProcessTargetSpec }
+  ) {
+    super(conn, {
+      isTopLevelTarget,
+      sessionContext,
+      customSpec,
+    });
+
+    // This creates a Debugger instance for chrome debugging all globals.
+    this.makeDebugger = makeDebugger.bind(null, {
+      findDebuggees: dbg => dbg.findAllGlobals(),
+      shouldAddNewGlobalAsDebuggee: () => true,
+    });
+
+    // Ensure catching the creation of any new content docshell
+    this.watchNewDocShells = true;
+
+    this.isRootActor = true;
+
+    // Listen for any new/destroyed chrome docshell
+    Services.obs.addObserver(this, "chrome-webnavigation-create");
+    Services.obs.addObserver(this, "chrome-webnavigation-destroy");
+
+    // If we are the parent process target actor and not a subclass
+    // (i.e. if we aren't the webext target actor)
+    // set the parent process docshell:
+    if (customSpec == parentProcessTargetSpec) {
+      this.setDocShell(this._getInitialDocShell());
+    }
+  }
+
+  // Overload setDocShell in order to observe all the docshells.
+  // WindowGlobalTargetActor only observes the top level one,
+  // but we also need to observe all of them for WebExtensionTargetActor subclass.
+  setDocShell(initialDocShell) {
+    super.setDocShell(initialDocShell);
+
+    // Iterate over all top-level windows.
+    for (const { docShell } of Services.ww.getWindowEnumerator()) {
+      if (docShell == this.docShell) {
+        continue;
+      }
+      this._progressListener.watch(docShell);
+    }
+  }
+
+  _getInitialDocShell() {
+    // Defines the default docshell selected for the target actor
+    let window = Services.wm.getMostRecentWindow(
+      DevToolsServer.chromeWindowType
+    );
+
+    // Default to any available top level window if there is no expected window
+    // eg when running ./mach run --chrome chrome://browser/content/aboutTabCrashed.xhtml --jsdebugger
+    if (!window) {
+      window = Services.wm.getMostRecentWindow(null);
+    }
+
+    // We really want _some_ window at least, so fallback to the hidden window if
+    // there's nothing else (such as during early startup).
+    if (!window) {
+      window = Services.appShell.hiddenDOMWindow;
+    }
+    return window.docShell;
+  }
+
+  /**
+   * Getter for the list of all docshells in this targetActor
+   * @return {Array}
+   */
+  get docShells() {
+    // Iterate over all top-level windows and all their docshells.
+    let docShells = [];
+    for (const { docShell } of Services.ww.getWindowEnumerator()) {
+      docShells = docShells.concat(getChildDocShells(docShell));
+    }
+
+    return docShells;
+  }
+
+  observe(subject, topic, data) {
+    super.observe(subject, topic, data);
+    if (this.isDestroyed()) {
+      return;
+    }
+
+    subject.QueryInterface(Ci.nsIDocShell);
+
+    if (topic == "chrome-webnavigation-create") {
+      this._onDocShellCreated(subject);
+    } else if (topic == "chrome-webnavigation-destroy") {
+      this._onDocShellDestroy(subject);
+    }
+  }
+
+  _detach() {
+    if (this.isDestroyed()) {
+      return false;
+    }
+
+    Services.obs.removeObserver(this, "chrome-webnavigation-create");
+    Services.obs.removeObserver(this, "chrome-webnavigation-destroy");
+
+    // Iterate over all top-level windows.
+    for (const { docShell } of Services.ww.getWindowEnumerator()) {
+      if (docShell == this.docShell) {
+        continue;
+      }
+      this._progressListener.unwatch(docShell);
+    }
+
+    return super._detach();
+  }
+}
+
+exports.ParentProcessTargetActor = ParentProcessTargetActor;
diff --git a/devtools/server/actors/targets/session-data-processors/blackboxing.js b/devtools/server/actors/targets/session-data-processors/blackboxing.js
new file mode 100644
index 0000000000..a81333f108
--- /dev/null
+++ b/devtools/server/actors/targets/session-data-processors/blackboxing.js
@@ -0,0 +1,19 @@
+/* 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";
+
+module.exports = {
+  async addSessionDataEntry(targetActor, entries, isDocumentCreation) {
+    for (const { url, range } of entries) {
+      targetActor.sourcesManager.blackBox(url, range);
+    }
+  },
+
+  removeSessionDataEntry(targetActor, entries, isDocumentCreation) {
+    for (const { url, range } of entries) {
+      targetActor.sourcesManager.unblackBox(url, range);
+    }
+  },
+};
diff --git a/devtools/server/actors/targets/session-data-processors/breakpoints.js b/devtools/server/actors/targets/session-data-processors/breakpoints.js
new file mode 100644
index 0000000000..a3c778be59
--- /dev/null
+++ b/devtools/server/actors/targets/session-data-processors/breakpoints.js
@@ -0,0 +1,37 @@
+/* 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";
+
+const {
+  STATES: THREAD_STATES,
+} = require("resource://devtools/server/actors/thread.js");
+
+module.exports = {
+  async addSessionDataEntry(targetActor, entries, isDocumentCreation) {
+    const isTargetCreation =
+      targetActor.threadActor.state == THREAD_STATES.DETACHED;
+    if (isTargetCreation && !targetActor.targetType.endsWith("worker")) {
+      // If addSessionDataEntry is called during target creation, attach the
+      // thread actor automatically and pass the initial breakpoints.
+      // However, do not attach the thread actor for Workers. They use a codepath
+      // which releases the worker on `attach`. For them, the client will call `attach`. (bug 1691986)
+      await targetActor.threadActor.attach({ breakpoints: entries });
+    } else {
+      // If addSessionDataEntry is called for an existing target, set the new
+      // breakpoints on the already running thread actor.
+      await Promise.all(
+        entries.map(({ location, options }) =>
+          targetActor.threadActor.setBreakpoint(location, options)
+        )
+      );
+    }
+  },
+
+  removeSessionDataEntry(targetActor, entries, isDocumentCreation) {
+    for (const { location } of entries) {
+      targetActor.threadActor.removeBreakpoint(location);
+    }
+  },
+};
diff --git a/devtools/server/actors/targets/session-data-processors/event-breakpoints.js b/devtools/server/actors/targets/session-data-processors/event-breakpoints.js
new file mode 100644
index 0000000000..5cd2004281
--- /dev/null
+++ b/devtools/server/actors/targets/session-data-processors/event-breakpoints.js
@@ -0,0 +1,26 @@
+/* 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";
+
+const {
+  STATES: THREAD_STATES,
+} = require("resource://devtools/server/actors/thread.js");
+
+module.exports = {
+  async addSessionDataEntry(targetActor, entries, isDocumentCreation) {
+    // Same as comments for XHR breakpoints. See lines 117-118
+    if (
+      targetActor.threadActor.state == THREAD_STATES.DETACHED &&
+      !targetActor.targetType.endsWith("worker")
+    ) {
+      targetActor.threadActor.attach();
+    }
+    targetActor.threadActor.addEventBreakpoints(entries);
+  },
+
+  removeSessionDataEntry(targetActor, entries, isDocumentCreation) {
+    targetActor.threadActor.removeEventBreakpoints(entries);
+  },
+};
diff --git a/devtools/server/actors/targets/session-data-processors/index.js b/devtools/server/actors/targets/session-data-processors/index.js
new file mode 100644
index 0000000000..19b7d69302
--- /dev/null
+++ b/devtools/server/actors/targets/session-data-processors/index.js
@@ -0,0 +1,50 @@
+/* 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";
+
+const {
+  SessionDataHelpers,
+} = require("resource://devtools/server/actors/watcher/SessionDataHelpers.jsm");
+const { SUPPORTED_DATA } = SessionDataHelpers;
+
+const SessionDataProcessors = {};
+
+loader.lazyRequireGetter(
+  SessionDataProcessors,
+  SUPPORTED_DATA.BLACKBOXING,
+  "resource://devtools/server/actors/targets/session-data-processors/blackboxing.js"
+);
+loader.lazyRequireGetter(
+  SessionDataProcessors,
+  SUPPORTED_DATA.BREAKPOINTS,
+  "resource://devtools/server/actors/targets/session-data-processors/breakpoints.js"
+);
+loader.lazyRequireGetter(
+  SessionDataProcessors,
+  SUPPORTED_DATA.EVENT_BREAKPOINTS,
+  "resource://devtools/server/actors/targets/session-data-processors/event-breakpoints.js"
+);
+loader.lazyRequireGetter(
+  SessionDataProcessors,
+  SUPPORTED_DATA.RESOURCES,
+  "resource://devtools/server/actors/targets/session-data-processors/resources.js"
+);
+loader.lazyRequireGetter(
+  SessionDataProcessors,
+  SUPPORTED_DATA.TARGET_CONFIGURATION,
+  "resource://devtools/server/actors/targets/session-data-processors/target-configuration.js"
+);
+loader.lazyRequireGetter(
+  SessionDataProcessors,
+  SUPPORTED_DATA.THREAD_CONFIGURATION,
+  "resource://devtools/server/actors/targets/session-data-processors/thread-configuration.js"
+);
+loader.lazyRequireGetter(
+  SessionDataProcessors,
+  SUPPORTED_DATA.XHR_BREAKPOINTS,
+  "resource://devtools/server/actors/targets/session-data-processors/xhr-breakpoints.js"
+);
+
+exports.SessionDataProcessors = SessionDataProcessors;
diff --git a/devtools/server/actors/targets/session-data-processors/moz.build b/devtools/server/actors/targets/session-data-processors/moz.build
new file mode 100644
index 0000000000..ea924d7d79
--- /dev/null
+++ b/devtools/server/actors/targets/session-data-processors/moz.build
@@ -0,0 +1,16 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+DevToolsModules(
+    "blackboxing.js",
+    "breakpoints.js",
+    "event-breakpoints.js",
+    "index.js",
+    "resources.js",
+    "target-configuration.js",
+    "thread-configuration.js",
+    "xhr-breakpoints.js",
+)
diff --git a/devtools/server/actors/targets/session-data-processors/resources.js b/devtools/server/actors/targets/session-data-processors/resources.js
new file mode 100644
index 0000000000..c784e128d3
--- /dev/null
+++ b/devtools/server/actors/targets/session-data-processors/resources.js
@@ -0,0 +1,17 @@
+/* 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";
+
+const Resources = require("resource://devtools/server/actors/resources/index.js");
+
+module.exports = {
+  async addSessionDataEntry(targetActor, entries, isDocumentCreation) {
+    await Resources.watchResources(targetActor, entries);
+  },
+
+  removeSessionDataEntry(targetActor, entries, isDocumentCreation) {
+    Resources.unwatchResources(targetActor, entries);
+  },
+};
diff --git a/devtools/server/actors/targets/session-data-processors/target-configuration.js b/devtools/server/actors/targets/session-data-processors/target-configuration.js
new file mode 100644
index 0000000000..e3fa7e0317
--- /dev/null
+++ b/devtools/server/actors/targets/session-data-processors/target-configuration.js
@@ -0,0 +1,23 @@
+/* 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";
+
+module.exports = {
+  async addSessionDataEntry(targetActor, entries, isDocumentCreation) {
+    // Only WindowGlobalTargetActor implements updateTargetConfiguration,
+    // skip targetActor data entry update for other targets.
+    if (typeof targetActor.updateTargetConfiguration == "function") {
+      const options = {};
+      for (const { key, value } of entries) {
+        options[key] = value;
+      }
+      targetActor.updateTargetConfiguration(options, isDocumentCreation);
+    }
+  },
+
+  removeSessionDataEntry(targetActor, entries, isDocumentCreation) {
+    // configuration data entries are always added/updated, never removed.
+  },
+};
diff --git a/devtools/server/actors/targets/session-data-processors/thread-configuration.js b/devtools/server/actors/targets/session-data-processors/thread-configuration.js
new file mode 100644
index 0000000000..e81ef819f0
--- /dev/null
+++ b/devtools/server/actors/targets/session-data-processors/thread-configuration.js
@@ -0,0 +1,32 @@
+/* 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";
+
+const {
+  STATES: THREAD_STATES,
+} = require("resource://devtools/server/actors/thread.js");
+
+module.exports = {
+  async addSessionDataEntry(targetActor, entries, isDocumentCreation) {
+    const threadOptions = {};
+
+    for (const { key, value } of entries) {
+      threadOptions[key] = value;
+    }
+
+    if (
+      !targetActor.targetType.endsWith("worker") &&
+      targetActor.threadActor.state == THREAD_STATES.DETACHED
+    ) {
+      await targetActor.threadActor.attach(threadOptions);
+    } else {
+      await targetActor.threadActor.reconfigure(threadOptions);
+    }
+  },
+
+  removeSessionDataEntry(targetActor, entries, isDocumentCreation) {
+    // configuration data entries are always added/updated, never removed.
+  },
+};
diff --git a/devtools/server/actors/targets/session-data-processors/xhr-breakpoints.js b/devtools/server/actors/targets/session-data-processors/xhr-breakpoints.js
new file mode 100644
index 0000000000..d9a9bdc750
--- /dev/null
+++ b/devtools/server/actors/targets/session-data-processors/xhr-breakpoints.js
@@ -0,0 +1,34 @@
+/* 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";
+
+const {
+  STATES: THREAD_STATES,
+} = require("resource://devtools/server/actors/thread.js");
+
+module.exports = {
+  async addSessionDataEntry(targetActor, entries, isDocumentCreation) {
+    // The thread actor has to be initialized in order to correctly
+    // retrieve the stack trace when hitting an XHR
+    if (
+      targetActor.threadActor.state == THREAD_STATES.DETACHED &&
+      !targetActor.targetType.endsWith("worker")
+    ) {
+      await targetActor.threadActor.attach();
+    }
+
+    await Promise.all(
+      entries.map(({ path, method }) =>
+        targetActor.threadActor.setXHRBreakpoint(path, method)
+      )
+    );
+  },
+
+  removeSessionDataEntry(targetActor, entries, isDocumentCreation) {
+    for (const { path, method } of entries) {
+      targetActor.threadActor.removeXHRBreakpoint(path, method);
+    }
+  },
+};
diff --git a/devtools/server/actors/targets/target-actor-registry.sys.mjs b/devtools/server/actors/targets/target-actor-registry.sys.mjs
new file mode 100644
index 0000000000..4cb6d13868
--- /dev/null
+++ b/devtools/server/actors/targets/target-actor-registry.sys.mjs
@@ -0,0 +1,82 @@
+/* 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/. */
+
+// Keep track of all WindowGlobal target actors.
+// This is especially used to track the actors using Message manager connector,
+// or the ones running in the parent process.
+// Top level actors, like tab's top level target or parent process target
+// are still using message manager in order to avoid being destroyed on navigation.
+// And because of this, these actors aren't using JS Window Actor.
+const windowGlobalTargetActors = new Set();
+let xpcShellTargetActor = null;
+
+export var TargetActorRegistry = {
+  registerTargetActor(targetActor) {
+    windowGlobalTargetActors.add(targetActor);
+  },
+
+  unregisterTargetActor(targetActor) {
+    windowGlobalTargetActors.delete(targetActor);
+  },
+
+  registerXpcShellTargetActor(targetActor) {
+    xpcShellTargetActor = targetActor;
+  },
+
+  unregisterXpcShellTargetActor(targetActor) {
+    xpcShellTargetActor = null;
+  },
+
+  get xpcShellTargetActor() {
+    return xpcShellTargetActor;
+  },
+
+  /**
+   * Return the target actors matching the passed browser element id.
+   * In some scenarios, the registry can have multiple target actors for a given
+   * browserId (e.g. the regular DevTools content toolbox + DevTools WebExtensions targets).
+   *
+   * @param {Object} sessionContext: The Session Context to help know what is debugged.
+   *                                 See devtools/server/actors/watcher/session-context.js
+   * @param {String} connectionPrefix: DevToolsServerConnection's prefix, in order to select only actor
+   *                                   related to the same connection. i.e. the same client.
+   * @returns {Array<TargetActor>}
+   */
+  getTargetActors(sessionContext, connectionPrefix) {
+    const actors = [];
+    for (const actor of windowGlobalTargetActors) {
+      const isMatchingPrefix = actor.actorID.startsWith(connectionPrefix);
+      const isMatchingContext =
+        sessionContext.type == "all" ||
+        (sessionContext.type == "browser-element" &&
+          (actor.browserId == sessionContext.browserId ||
+            actor.openerBrowserId == sessionContext.browserId)) ||
+        (sessionContext.type == "webextension" &&
+          actor.addonId == sessionContext.addonId);
+      if (isMatchingPrefix && isMatchingContext) {
+        actors.push(actor);
+      }
+    }
+    return actors;
+  },
+
+  /**
+   * Helper for tests to help track the number of targets created for a given tab.
+   * (Used by browser_ext_devtools_inspectedWindow.js)
+   *
+   * @param {Number} browserId: ID for the tab
+   *
+   * @returns {Number} Number of targets for this tab.
+   */
+
+  getTargetActorsCountForBrowserElement(browserId) {
+    let count = 0;
+    for (const actor of windowGlobalTargetActors) {
+      if (actor.browserId == browserId) {
+        count++;
+      }
+    }
+    return count;
+  },
+};
diff --git a/devtools/server/actors/targets/webextension.js b/devtools/server/actors/targets/webextension.js
new file mode 100644
index 0000000000..e94580378a
--- /dev/null
+++ b/devtools/server/actors/targets/webextension.js
@@ -0,0 +1,371 @@
+/* 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";
+
+/*
+ * Target actor for a WebExtension add-on.
+ *
+ * This actor extends ParentProcessTargetActor.
+ *
+ * See devtools/docs/backend/actor-hierarchy.md for more details.
+ */
+
+const {
+  ParentProcessTargetActor,
+} = require("resource://devtools/server/actors/targets/parent-process.js");
+const makeDebugger = require("resource://devtools/server/actors/utils/make-debugger.js");
+const {
+  webExtensionTargetSpec,
+} = require("resource://devtools/shared/specs/targets/webextension.js");
+
+const {
+  getChildDocShells,
+} = require("resource://devtools/server/actors/targets/window-global.js");
+
+loader.lazyRequireGetter(
+  this,
+  "unwrapDebuggerObjectGlobal",
+  "resource://devtools/server/actors/thread.js",
+  true
+);
+
+const lazy = {};
+ChromeUtils.defineESModuleGetters(lazy, {
+  getAddonIdForWindowGlobal:
+    "resource://devtools/server/actors/watcher/browsing-context-helpers.sys.mjs",
+});
+
+const FALLBACK_DOC_URL =
+  "chrome://devtools/content/shared/webextension-fallback.html";
+
+class WebExtensionTargetActor extends ParentProcessTargetActor {
+  /**
+   * Creates a target actor for debugging all the contexts associated to a target
+   * WebExtensions add-on running in a child extension process. Most of the implementation
+   * is inherited from ParentProcessTargetActor (which inherits most of its implementation
+   * from WindowGlobalTargetActor).
+   *
+   * WebExtensionTargetActor is created by a WebExtensionActor counterpart, when its
+   * parent actor's `connect` method has been called (on the listAddons RDP package),
+   * it runs in the same process that the extension is running into (which can be the main
+   * process if the extension is running in non-oop mode, or the child extension process
+   * if the extension is running in oop-mode).
+   *
+   * A WebExtensionTargetActor contains all target-scoped actors, like a regular
+   * ParentProcessTargetActor or WindowGlobalTargetActor.
+   *
+   * History lecture:
+   * - The add-on actors used to not inherit WindowGlobalTargetActor because of the
+   *   different way the add-on APIs where exposed to the add-on itself, and for this reason
+   *   the Addon Debugger has only a sub-set of the feature available in the Tab or in the
+   *   Browser Toolbox.
+   * - In a WebExtensions add-on all the provided contexts (background, popups etc.),
+   *   besides the Content Scripts which run in the content process, hooked to an existent
+   *   tab, by creating a new WebExtensionActor which inherits from
+   *   ParentProcessTargetActor, we can provide a full features Addon Toolbox (which is
+   *   basically like a BrowserToolbox which filters the visible sources and frames to the
+   *   one that are related to the target add-on).
+   * - When the WebExtensions OOP mode has been introduced, this actor has been refactored
+   *   and moved from the main process to the new child extension process.
+   *
+   * @param {DevToolsServerConnection} conn
+   *        The connection to the client.
+   * @param {nsIMessageSender} chromeGlobal.
+   *        The chromeGlobal where this actor has been injected by the
+   *        frame-connector.js connectToFrame method.
+   * @param {Object} options
+   *        - addonId: {String} the addonId of the target WebExtension.
+   *        - addonBrowsingContextGroupId: {String} the BrowsingContextGroupId used by this addon.
+   *        - chromeGlobal: {nsIMessageSender} The chromeGlobal where this actor
+   *          has been injected by the frame-connector.js connectToFrame method.
+   *        - isTopLevelTarget: {Boolean} flag to indicate if this is the top
+   *          level target of the DevTools session
+   *        - prefix: {String} the custom RDP prefix to use.
+   *        - sessionContext Object
+   *          The Session Context to help know what is debugged.
+   *          See devtools/server/actors/watcher/session-context.js
+   */
+  constructor(
+    conn,
+    {
+      addonId,
+      addonBrowsingContextGroupId,
+      chromeGlobal,
+      isTopLevelTarget,
+      prefix,
+      sessionContext,
+    }
+  ) {
+    super(conn, {
+      isTopLevelTarget,
+      sessionContext,
+      customSpec: webExtensionTargetSpec,
+    });
+
+    this.addonId = addonId;
+    this.addonBrowsingContextGroupId = addonBrowsingContextGroupId;
+    this._chromeGlobal = chromeGlobal;
+    this._prefix = prefix;
+
+    // Expose the BrowsingContext of the fallback document,
+    // which is the one this target actor will always refer to via its form()
+    // and all resources should be related to this one as we currently spawn
+    // only just this one target actor to debug all webextension documents.
+    this.devtoolsSpawnedBrowsingContextForWebExtension =
+      chromeGlobal.browsingContext;
+
+    // Redefine the messageManager getter to return the chromeGlobal
+    // as the messageManager for this actor (which is the browser XUL
+    // element used by the parent actor running in the main process to
+    // connect to the extension process).
+    Object.defineProperty(this, "messageManager", {
+      enumerable: true,
+      configurable: true,
+      get: () => {
+        return this._chromeGlobal;
+      },
+    });
+
+    this._onParentExit = this._onParentExit.bind(this);
+
+    this._chromeGlobal.addMessageListener(
+      "debug:webext_parent_exit",
+      this._onParentExit
+    );
+
+    // Set the consoleAPIListener filtering options
+    // (retrieved and used in the related webconsole child actor).
+    this.consoleAPIListenerOptions = {
+      addonId: this.addonId,
+    };
+
+    // This creates a Debugger instance for debugging all the add-on globals.
+    this.makeDebugger = makeDebugger.bind(null, {
+      findDebuggees: dbg => {
+        return dbg.findAllGlobals().filter(this._shouldAddNewGlobalAsDebuggee);
+      },
+      shouldAddNewGlobalAsDebuggee:
+        this._shouldAddNewGlobalAsDebuggee.bind(this),
+    });
+
+    // NOTE: This is needed to catch in the webextension webconsole all the
+    // errors raised by the WebExtension internals that are not currently
+    // associated with any window.
+    this.isRootActor = true;
+
+    // Try to discovery an existent extension page to attach (which will provide the initial
+    // URL shown in the window tittle when the addon debugger is opened).
+    const extensionWindow = this._searchForExtensionWindow();
+    this.setDocShell(extensionWindow.docShell);
+  }
+
+  // Override the ParentProcessTargetActor's override in order to only iterate
+  // over the docshells specific to this add-on
+  get docShells() {
+    // Iterate over all top-level windows and all their docshells.
+    let docShells = [];
+    for (const window of Services.ww.getWindowEnumerator(null)) {
+      docShells = docShells.concat(getChildDocShells(window.docShell));
+    }
+    // Then filter out the ones specific to the add-on
+    return docShells.filter(docShell => {
+      return this.isExtensionWindowDescendent(docShell.domWindow);
+    });
+  }
+
+  /**
+   * Called when the actor is removed from the connection.
+   */
+  destroy() {
+    if (this._chromeGlobal) {
+      const chromeGlobal = this._chromeGlobal;
+      this._chromeGlobal = null;
+
+      chromeGlobal.removeMessageListener(
+        "debug:webext_parent_exit",
+        this._onParentExit
+      );
+
+      chromeGlobal.sendAsyncMessage("debug:webext_child_exit", {
+        actor: this.actorID,
+      });
+    }
+
+    if (this.fallbackWindow) {
+      this.fallbackWindow = null;
+    }
+
+    this.addon = null;
+    this.addonId = null;
+
+    return super.destroy();
+  }
+
+  // Private helpers.
+
+  _searchFallbackWindow() {
+    if (this.fallbackWindow) {
+      // Skip if there is already an existent fallback window.
+      return this.fallbackWindow;
+    }
+
+    // Set and initialize the fallbackWindow (which initially is a empty
+    // about:blank browser), this window is related to a XUL browser element
+    // specifically created for the devtools server and it is never used
+    // or navigated anywhere else.
+    this.fallbackWindow = this._chromeGlobal.content;
+
+    // Add the addonId in the URL to retrieve this information in other devtools
+    // helpers. The addonId is usually populated in the principal, but this will
+    // not be the case for the fallback window because it is loaded from chrome://
+    // instead of moz-extension://${addonId}
+    this.fallbackWindow.document.location.href = `${FALLBACK_DOC_URL}#${this.addonId}`;
+
+    return this.fallbackWindow;
+  }
+
+  // Discovery an extension page to use as a default target window.
+  // NOTE: This currently fail to discovery an extension page running in a
+  // windowless browser when running in non-oop mode, and the background page
+  // is set later using _onNewExtensionWindow.
+  _searchForExtensionWindow() {
+    // Looks if there is any top level add-on document:
+    // (we do not want to pass any nested add-on iframe)
+    const docShell = this.docShells.find(d =>
+      this.isTopLevelExtensionWindow(d.domWindow)
+    );
+    if (docShell) {
+      return docShell.domWindow;
+    }
+
+    return this._searchFallbackWindow();
+  }
+
+  // Customized ParentProcessTargetActor/WindowGlobalTargetActor hooks.
+
+  _onDocShellCreated(docShell) {
+    // Compare against the BrowsingContext's group ID as the document's principal addonId
+    // won't be set yet for freshly created docshells. It will be later set, when loading the addon URL.
+    // But right now, it is still on the initial about:blank document and the principal isn't related to the add-on.
+    if (docShell.browsingContext.group.id != this.addonBrowsingContextGroupId) {
+      return;
+    }
+    super._onDocShellCreated(docShell);
+  }
+
+  _onDocShellDestroy(docShell) {
+    if (docShell.browsingContext.group.id != this.addonBrowsingContextGroupId) {
+      return;
+    }
+    // Stop watching this docshell (the unwatch() method will check if we
+    // started watching it before).
+    this._unwatchDocShell(docShell);
+
+    // Let the _onDocShellDestroy notify that the docShell has been destroyed.
+    const webProgress = docShell
+      .QueryInterface(Ci.nsIInterfaceRequestor)
+      .getInterface(Ci.nsIWebProgress);
+    this._notifyDocShellDestroy(webProgress);
+
+    // If the destroyed docShell:
+    // * was the current docShell,
+    // * the actor is not destroyed,
+    // * isn't the background page, as it means the addon is being shutdown or reloaded
+    //   and the target would be replaced by a new one to come, or everything is closing.
+    // => switch to the fallback window
+    if (
+      !this.isDestroyed() &&
+      docShell == this.docShell &&
+      !docShell.domWindow.location.href.includes(
+        "_generated_background_page.html"
+      )
+    ) {
+      this._changeTopLevelDocument(this._searchForExtensionWindow());
+    }
+  }
+
+  _onNewExtensionWindow(window) {
+    if (!this.window || this.window === this.fallbackWindow) {
+      this._changeTopLevelDocument(window);
+      // For new extension windows, the BrowsingContext group id might have
+      // changed, for instance when reloading the addon.
+      this.addonBrowsingContextGroupId =
+        window.docShell.browsingContext.group.id;
+    }
+  }
+
+  isTopLevelExtensionWindow(window) {
+    const { docShell } = window;
+    const isTopLevel = docShell.sameTypeRootTreeItem == docShell;
+    // Note: We are not using getAddonIdForWindowGlobal here because the
+    // fallback window should not be considered as a top level extension window.
+    return isTopLevel && window.document.nodePrincipal.addonId == this.addonId;
+  }
+
+  isExtensionWindowDescendent(window) {
+    // Check if the source is coming from a descendant docShell of an extension window.
+    // We may have an iframe that loads http content which won't use the add-on principal.
+    const rootWin = window.docShell.sameTypeRootTreeItem.domWindow;
+    const addonId = lazy.getAddonIdForWindowGlobal(rootWin.windowGlobalChild);
+    return addonId == this.addonId;
+  }
+
+  /**
+   * Return true if the given global is associated with this addon and should be
+   * added as a debuggee, false otherwise.
+   */
+  _shouldAddNewGlobalAsDebuggee(newGlobal) {
+    const global = unwrapDebuggerObjectGlobal(newGlobal);
+
+    if (global instanceof Ci.nsIDOMWindow) {
+      try {
+        global.document;
+      } catch (e) {
+        // The global might be a sandbox with a window object in its proto chain. If the
+        // window navigated away since the sandbox was created, it can throw a security
+        // exception during this property check as the sandbox no longer has access to
+        // its own proto.
+        return false;
+      }
+      // When `global` is a sandbox it may be a nsIDOMWindow object,
+      // but won't be the real Window object. Retrieve it via document's ownerGlobal.
+      const window = global.document.ownerGlobal;
+      if (!window) {
+        return false;
+      }
+
+      // Change top level document as a simulated frame switching.
+      if (this.isTopLevelExtensionWindow(window)) {
+        this._onNewExtensionWindow(window);
+      }
+
+      return this.isExtensionWindowDescendent(window);
+    }
+
+    try {
+      // This will fail for non-Sandbox objects, hence the try-catch block.
+      const metadata = Cu.getSandboxMetadata(global);
+      if (metadata) {
+        return metadata.addonID === this.addonId;
+      }
+    } catch (e) {
+      // Unable to retrieve the sandbox metadata.
+    }
+
+    return false;
+  }
+
+  // Handlers for the messages received from the parent actor.
+
+  _onParentExit(msg) {
+    if (msg.json.actor !== this.actorID) {
+      return;
+    }
+
+    this.destroy();
+  }
+}
+
+exports.WebExtensionTargetActor = WebExtensionTargetActor;
diff --git a/devtools/server/actors/targets/window-global.js b/devtools/server/actors/targets/window-global.js
new file mode 100644
index 0000000000..0a7df9c272
--- /dev/null
+++ b/devtools/server/actors/targets/window-global.js
@@ -0,0 +1,1932 @@
+/* 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";
+
+// protocol.js uses objects as exceptions in order to define
+// error packets.
+/* eslint-disable no-throw-literal */
+
+/*
+ * WindowGlobalTargetActor is an abstract class used by target actors that hold
+ * documents, such as frames, chrome windows, etc.
+ *
+ * This class is extended by ParentProcessTargetActor, itself being extented by WebExtensionTargetActor.
+ *
+ * See devtools/docs/backend/actor-hierarchy.md for more details.
+ *
+ * For performance matters, this file should only be loaded in the targeted context's
+ * process. For example, it shouldn't be evaluated in the parent process until we try to
+ * debug a document living in the parent process.
+ */
+
+var {
+  ActorRegistry,
+} = require("resource://devtools/server/actors/utils/actor-registry.js");
+var DevToolsUtils = require("resource://devtools/shared/DevToolsUtils.js");
+var { assert } = DevToolsUtils;
+var {
+  SourcesManager,
+} = require("resource://devtools/server/actors/utils/sources-manager.js");
+var makeDebugger = require("resource://devtools/server/actors/utils/make-debugger.js");
+const Targets = require("resource://devtools/server/actors/targets/index.js");
+const { TargetActorRegistry } = ChromeUtils.importESModule(
+  "resource://devtools/server/actors/targets/target-actor-registry.sys.mjs",
+  {
+    loadInDevToolsLoader: false,
+  }
+);
+const { PrivateBrowsingUtils } = ChromeUtils.importESModule(
+  "resource://gre/modules/PrivateBrowsingUtils.sys.mjs"
+);
+
+const EXTENSION_CONTENT_SYS_MJS =
+  "resource://gre/modules/ExtensionContent.sys.mjs";
+
+const { Pool } = require("resource://devtools/shared/protocol.js");
+const {
+  LazyPool,
+  createExtraActors,
+} = require("resource://devtools/shared/protocol/lazy-pool.js");
+const {
+  windowGlobalTargetSpec,
+} = require("resource://devtools/shared/specs/targets/window-global.js");
+const Resources = require("resource://devtools/server/actors/resources/index.js");
+const {
+  BaseTargetActor,
+} = require("resource://devtools/server/actors/targets/base-target-actor.js");
+
+loader.lazyRequireGetter(
+  this,
+  ["ThreadActor", "unwrapDebuggerObjectGlobal"],
+  "resource://devtools/server/actors/thread.js",
+  true
+);
+loader.lazyRequireGetter(
+  this,
+  "WorkerDescriptorActorList",
+  "resource://devtools/server/actors/worker/worker-descriptor-actor-list.js",
+  true
+);
+loader.lazyRequireGetter(
+  this,
+  "StyleSheetsManager",
+  "resource://devtools/server/actors/utils/stylesheets-manager.js",
+  true
+);
+const lazy = {};
+loader.lazyGetter(lazy, "ExtensionContent", () => {
+  return ChromeUtils.importESModule(EXTENSION_CONTENT_SYS_MJS, {
+    // ExtensionContent.sys.mjs is a singleton and must be loaded through the
+    // main loader. Note that the user of lazy.ExtensionContent elsewhere in
+    // this file (at webextensionsContentScriptGlobals) looks up the module
+    // via Cu.isESModuleLoaded, which also uses the main loader as desired.
+    loadInDevToolsLoader: false,
+  }).ExtensionContent;
+});
+
+loader.lazyRequireGetter(
+  this,
+  "TouchSimulator",
+  "resource://devtools/server/actors/emulation/touch-simulator.js",
+  true
+);
+
+function getWindowID(window) {
+  return window.windowGlobalChild.innerWindowId;
+}
+
+function getDocShellChromeEventHandler(docShell) {
+  let handler = docShell.chromeEventHandler;
+  if (!handler) {
+    try {
+      // Toplevel xul window's docshell doesn't have chromeEventHandler
+      // attribute. The chrome event handler is just the global window object.
+      handler = docShell.domWindow;
+    } catch (e) {
+      // ignore
+    }
+  }
+  return handler;
+}
+
+/**
+ * Helper to retrieve all children docshells of a given docshell.
+ *
+ * Given that docshell interfaces can only be used within the same process,
+ * this only returns docshells for children documents that runs in the same process
+ * as the given docshell.
+ */
+function getChildDocShells(parentDocShell) {
+  return parentDocShell.browsingContext
+    .getAllBrowsingContextsInSubtree()
+    .filter(browsingContext => {
+      // Filter out browsingContext which don't expose any docshell (e.g. remote frame)
+      return browsingContext.docShell;
+    })
+    .map(browsingContext => {
+      // Map BrowsingContext to DocShell
+      return browsingContext.docShell;
+    });
+}
+
+exports.getChildDocShells = getChildDocShells;
+
+/**
+ * Browser-specific actors.
+ */
+
+function getInnerId(window) {
+  return window.windowGlobalChild.innerWindowId;
+}
+
+class WindowGlobalTargetActor extends BaseTargetActor {
+  /**
+   * WindowGlobalTargetActor is the target actor to debug (HTML) documents.
+   *
+   * WindowGlobal's are the Gecko representation for a given document's window object.
+   * It relates to a given nsGlobalWindowInner instance.
+   *
+   * The main goal of this class is to expose the target-scoped actors being registered
+   * via `ActorRegistry.registerModule` and manage their lifetimes. In addition, this
+   * class also tracks the lifetime of the targeted window global.
+   *
+   * ### Main requests:
+   *
+   * `detach`:
+   *  Stop document watching and cleanup everything that the target and its children actors created.
+   *  It ultimately lead to destroy the target actor.
+   * `switchToFrame`:
+   *  Change the targeted document of the whole actor, and its child target-scoped actors
+   *  to an iframe or back to its original document.
+   *
+   * Most properties (like `chromeEventHandler` or `docShells`) are meant to be
+   * used by the various child target actors.
+   *
+   * ### RDP events:
+   *
+   *  - `tabNavigated`:
+   *    Sent when the window global is about to navigate or has just navigated
+   *    to a different document.
+   *    This event contains the following attributes:
+   *     * url (string)
+   *       The new URI being loaded.
+   *     * state (string)
+   *       `start` if we just start requesting the new URL
+   *       `stop`  if the new URL is done loading
+   *     * isFrameSwitching (boolean)
+   *       Indicates the event is dispatched when switching the actor context to a
+   *       different frame. When we switch to an iframe, there is no document
+   *       load. The targeted document is most likely going to be already done
+   *       loading.
+   *     * title (string)
+   *       The document title being loaded. (sent only on state=stop)
+   *
+   *  - `frameUpdate`:
+   *    Sent when there was a change in the child frames contained in the document
+   *    or when the actor's context was switched to another frame.
+   *    This event can have four different forms depending on the type of change:
+   *    * One or many frames are updated:
+   *      { frames: [{ id, url, title, parentID }, ...] }
+   *    * One frame got destroyed:
+   *      { frames: [{ id, destroy: true }]}
+   *    * All frames got destroyed:
+   *      { destroyAll: true }
+   *    * We switched the context of the actor to a specific frame:
+   *      { selected: #id }
+   *
+   * ### Internal, non-rdp events:
+   *
+   * Various events are also dispatched on the actor itself without being sent to
+   * the client. They all relate to the documents tracked by this target actor
+   * (its main targeted document, but also any of its iframes):
+   *  - will-navigate
+   *    This event fires once navigation starts. All pending user prompts are
+   *    dealt with, but it is fired before the first request starts.
+   *  - navigate
+   *    This event is fired once the document's readyState is "complete".
+   *  - window-ready
+   *    This event is fired in various distinct scenarios:
+   *     * When a new Window object is crafted, equivalent of `DOMWindowCreated`.
+   *       It is dispatched before any page script is executed.
+   *     * We will have already received a window-ready event for this window
+   *       when it was created, but we received a window-destroyed event when
+   *       it was frozen into the bfcache, and now the user navigated back to
+   *       this page, so it's now live again and we should resume handling it.
+   *     * For each existing document, when an `attach` request is received.
+   *       At this point scripts in the page will be already loaded.
+   *     * When `swapFrameLoaders` is used, such as with moving window globals
+   *       between windows or toggling Responsive Design Mode.
+   *  - window-destroyed
+   *    This event is fired in two cases:
+   *     * When the window object is destroyed, i.e. when the related document
+   *       is garbage collected. This can happen when the window global is
+   *       closed or the iframe is removed from the DOM.
+   *       It is equivalent of `inner-window-destroyed` event.
+   *     * When the page goes into the bfcache and gets frozen.
+   *       The equivalent of `pagehide`.
+   *  - changed-toplevel-document
+   *    This event fires when we switch the actor's targeted document
+   *    to one of its iframes, or back to its original top document.
+   *    It is dispatched between window-destroyed and window-ready.
+   *
+   * Note that *all* these events are dispatched in the following order
+   * when we switch the context of the actor to a given iframe:
+   *  - will-navigate
+   *  - window-destroyed
+   *  - changed-toplevel-document
+   *  - window-ready
+   *  - navigate
+   *
+   * This class is subclassed by ParentProcessTargetActor and others.
+   * Subclasses are expected to implement a getter for the docShell property.
+   *
+   * @param conn DevToolsServerConnection
+   *        The conection to the client.
+   * @param options Object
+   *        Object with following attributes:
+   *        - docShell nsIDocShell
+   *          The |docShell| for the debugged frame.
+   *        - followWindowGlobalLifeCycle Boolean
+   *          If true, the target actor will only inspect the current WindowGlobal (and its children windows).
+   *          But won't inspect next document loaded in the same BrowsingContext.
+   *          The actor will behave more like a WindowGlobalTarget rather than a BrowsingContextTarget.
+   *          This is always true for Tab debugging, but not yet for parent process/web extension.
+   *        - isTopLevelTarget Boolean
+   *          Should be set to true for all top-level targets. A top level target
+   *          is the topmost target of a DevTools "session". For instance for a local
+   *          tab toolbox, the WindowGlobalTargetActor for the content page is the top level target.
+   *          For the Multiprocess Browser Toolbox, the parent process target is the top level
+   *          target.
+   *          At the moment this only impacts the WindowGlobalTarget `reconfigure`
+   *          implementation. But for server-side target switching this flag will be exposed
+   *          to the client and should be available for all target actor classes. It will be
+   *          used to detect target switching. (Bug 1644397)
+   *        - ignoreSubFrames Boolean
+   *          If true, the actor will only focus on the passed docShell and not on the whole
+   *          docShell tree. This should be enabled when we have targets for all documents.
+   *        - sessionContext Object
+   *          The Session Context to help know what is debugged.
+   *          See devtools/server/actors/watcher/session-context.js
+   */
+  constructor(
+    conn,
+    {
+      docShell,
+      followWindowGlobalLifeCycle,
+      isTopLevelTarget,
+      ignoreSubFrames,
+      sessionContext,
+      customSpec = windowGlobalTargetSpec,
+    }
+  ) {
+    super(conn, Targets.TYPES.FRAME, customSpec);
+
+    this.followWindowGlobalLifeCycle = followWindowGlobalLifeCycle;
+    this.isTopLevelTarget = !!isTopLevelTarget;
+    this.ignoreSubFrames = ignoreSubFrames;
+    this.sessionContext = sessionContext;
+
+    // A map of actor names to actor instances provided by extensions.
+    this._extraActors = {};
+    this._sourcesManager = null;
+
+    this._shouldAddNewGlobalAsDebuggee =
+      this._shouldAddNewGlobalAsDebuggee.bind(this);
+
+    this.makeDebugger = makeDebugger.bind(null, {
+      findDebuggees: () => {
+        const result = [];
+        const inspectUAWidgets = Services.prefs.getBoolPref(
+          "devtools.inspector.showAllAnonymousContent",
+          false
+        );
+        for (const win of this.windows) {
+          result.push(win);
+          // Only expose User Agent internal (like <video controls>) when the
+          // related pref is set.
+          if (inspectUAWidgets) {
+            const principal = win.document.nodePrincipal;
+            // We don't use UA widgets for the system principal.
+            if (!principal.isSystemPrincipal) {
+              result.push(Cu.getUAWidgetScope(principal));
+            }
+          }
+        }
+        return result.concat(this.webextensionsContentScriptGlobals);
+      },
+      shouldAddNewGlobalAsDebuggee: this._shouldAddNewGlobalAsDebuggee,
+    });
+
+    // Flag eventually overloaded by sub classes in order to watch new docshells
+    // Used by the ParentProcessTargetActor to list all frames in the Browser Toolbox
+    this.watchNewDocShells = false;
+
+    this._workerDescriptorActorList = null;
+    this._workerDescriptorActorPool = null;
+    this._onWorkerDescriptorActorListChanged =
+      this._onWorkerDescriptorActorListChanged.bind(this);
+
+    this._onConsoleApiProfilerEvent =
+      this._onConsoleApiProfilerEvent.bind(this);
+    Services.obs.addObserver(
+      this._onConsoleApiProfilerEvent,
+      "console-api-profiler"
+    );
+
+    // Start observing navigations as well as sub documents.
+    // (This is probably meant to disappear once EFT is the only supported codepath)
+    this._progressListener = new DebuggerProgressListener(this);
+
+    TargetActorRegistry.registerTargetActor(this);
+
+    if (docShell) {
+      this.setDocShell(docShell);
+    }
+  }
+
+  /**
+   * Define the initial docshell.
+   *
+   * This is called from the constructor for WindowGlobalTargetActor,
+   * or from sub class constructors: WebExtensionTargetActor and ParentProcessTargetActor.
+   *
+   * This is to circumvent the fact that sub classes need to call inner method
+   * to compute the initial docshell and we can't call inner methods before calling
+   * the base class constructor...
+   */
+  setDocShell(docShell) {
+    Object.defineProperty(this, "docShell", {
+      value: docShell,
+      configurable: true,
+      writable: true,
+    });
+
+    // Save references to the original document we attached to
+    this._originalWindow = this.window;
+
+    // Update isPrivate as window is based on docShell
+    this.isPrivate = PrivateBrowsingUtils.isContentWindowPrivate(this.window);
+
+    // Instantiate the Thread Actor immediately.
+    // This is the only one actor instantiated right away by the target actor.
+    // All the others are instantiated lazily on first request made the client,
+    // via LazyPool API.
+    this._createThreadActor();
+
+    // Ensure notifying about the target actor first
+    // before notifying about new docshells.
+    // Otherwise we would miss these RDP event as the client hasn't
+    // yet received the target actor's form.
+    // (This is also probably meant to disappear once EFT is the only supported codepath)
+    this._docShellsObserved = false;
+    DevToolsUtils.executeSoon(() => this._watchDocshells());
+  }
+
+  get docShell() {
+    throw new Error(
+      "A docShell should be provided as constructor argument of WindowGlobalTargetActor, or redefined by the subclass"
+    );
+  }
+
+  // Optional console API listener options (e.g. used by the WebExtensionActor to
+  // filter console messages by addonID), set to an empty (no options) object by default.
+  consoleAPIListenerOptions = {};
+
+  /*
+   * Return a Debugger instance or create one if there is none yet
+   */
+  get dbg() {
+    if (!this._dbg) {
+      this._dbg = this.makeDebugger();
+    }
+    return this._dbg;
+  }
+
+  /**
+   * Try to locate the console actor if it exists.
+   */
+  get _consoleActor() {
+    if (this.isDestroyed()) {
+      return null;
+    }
+    const form = this.form();
+    return this.conn._getOrCreateActor(form.consoleActor);
+  }
+
+  get _memoryActor() {
+    if (this.isDestroyed()) {
+      return null;
+    }
+    const form = this.form();
+    return this.conn._getOrCreateActor(form.memoryActor);
+  }
+
+  _targetScopedActorPool = null;
+
+  /**
+   * An object on which listen for DOMWindowCreated and pageshow events.
+   */
+  get chromeEventHandler() {
+    return getDocShellChromeEventHandler(this.docShell);
+  }
+
+  /**
+   * Getter for the nsIMessageManager associated to the window global.
+   */
+  get messageManager() {
+    try {
+      return this.docShell.messageManager;
+    } catch (e) {
+      // In some cases we can't get a docshell.  We just have no message manager
+      // then,
+      return null;
+    }
+  }
+
+  /**
+   * Getter for the list of all `docShell`s in the window global.
+   * @return {Array}
+   */
+  get docShells() {
+    if (this.ignoreSubFrames) {
+      return [this.docShell];
+    }
+
+    return getChildDocShells(this.docShell);
+  }
+
+  /**
+   * Getter for the window global's current DOM window.
+   */
+  get window() {
+    return this.docShell && !this.docShell.isBeingDestroyed()
+      ? this.docShell.domWindow
+      : null;
+  }
+
+  get outerWindowID() {
+    if (this.docShell) {
+      return this.docShell.outerWindowID;
+    }
+    return null;
+  }
+
+  get browsingContext() {
+    return this.docShell?.browsingContext;
+  }
+
+  get browsingContextID() {
+    return this.browsingContext?.id;
+  }
+
+  get browserId() {
+    return this.browsingContext?.browserId;
+  }
+
+  get openerBrowserId() {
+    return this.browsingContext?.opener?.browserId;
+  }
+
+  /**
+   * Getter for the WebExtensions ContentScript globals related to the
+   * window global's current DOM window.
+   */
+  get webextensionsContentScriptGlobals() {
+    // Only retrieve the content scripts globals if the ExtensionContent JSM module
+    // has been already loaded (which is true if the WebExtensions internals have already
+    // been loaded in the same content process).
+    if (Cu.isESModuleLoaded(EXTENSION_CONTENT_SYS_MJS)) {
+      return lazy.ExtensionContent.getContentScriptGlobals(this.window);
+    }
+
+    return [];
+  }
+
+  /**
+   * Getter for the list of all content DOM windows in the window global.
+   * @return {Array}
+   */
+  get windows() {
+    return this.docShells.map(docShell => {
+      return docShell.domWindow;
+    });
+  }
+
+  /**
+   * Getter for the original docShell this actor got attached to in the first
+   * place.
+   * Note that your actor should normally *not* rely on this top level docShell
+   * if you want it to show information relative to the iframe that's currently
+   * being inspected in the toolbox.
+   */
+  get originalDocShell() {
+    if (!this._originalWindow) {
+      return this.docShell;
+    }
+
+    return this._originalWindow.docShell;
+  }
+
+  /**
+   * Getter for the original window this actor got attached to in the first
+   * place.
+   * Note that your actor should normally *not* rely on this top level window if
+   * you want it to show information relative to the iframe that's currently
+   * being inspected in the toolbox.
+   */
+  get originalWindow() {
+    return this._originalWindow || this.window;
+  }
+
+  /**
+   * Getter for the nsIWebProgress for watching this window.
+   */
+  get webProgress() {
+    return this.docShell
+      .QueryInterface(Ci.nsIInterfaceRequestor)
+      .getInterface(Ci.nsIWebProgress);
+  }
+
+  /**
+   * Getter for the nsIWebNavigation for the target.
+   */
+  get webNavigation() {
+    return this.docShell.QueryInterface(Ci.nsIWebNavigation);
+  }
+
+  /**
+   * Getter for the window global's document.
+   */
+  get contentDocument() {
+    return this.webNavigation.document;
+  }
+
+  /**
+   * Getter for the window global's title.
+   */
+  get title() {
+    return this.contentDocument.title;
+  }
+
+  /**
+   * Getter for the window global's URL.
+   */
+  get url() {
+    if (this.webNavigation.currentURI) {
+      return this.webNavigation.currentURI.spec;
+    }
+    // Abrupt closing of the browser window may leave callbacks without a
+    // currentURI.
+    return null;
+  }
+
+  get sourcesManager() {
+    if (!this._sourcesManager) {
+      this._sourcesManager = new SourcesManager(this.threadActor);
+    }
+    return this._sourcesManager;
+  }
+
+  getStyleSheetsManager() {
+    if (!this._styleSheetsManager) {
+      this._styleSheetsManager = new StyleSheetsManager(this);
+    }
+    return this._styleSheetsManager;
+  }
+
+  _createExtraActors() {
+    // Always use the same Pool, so existing actor instances
+    // (created in createExtraActors) are not lost.
+    if (!this._targetScopedActorPool) {
+      this._targetScopedActorPool = new LazyPool(this.conn);
+    }
+
+    // Walk over target-scoped actor factories and make sure they are all
+    // instantiated and added into the Pool.
+    return createExtraActors(
+      ActorRegistry.targetScopedActorFactories,
+      this._targetScopedActorPool,
+      this
+    );
+  }
+
+  form() {
+    assert(
+      !this.isDestroyed(),
+      "form() shouldn't be called on destroyed browser actor."
+    );
+    assert(this.actorID, "Actor should have an actorID.");
+
+    // Note that we don't want the iframe dropdown to change our BrowsingContext.id/innerWindowId
+    // We only want to refer to the topmost original window we attached to
+    // as that's the one top document this target actor really represent.
+    // The iframe dropdown is just a hack that temporarily focus the scope
+    // of the target actor to a children iframe document.
+    //
+    // Also, for WebExtension, we want the target to represent the <browser> element
+    // created by DevTools, which always exists and help better connect resources to the target
+    // in the frontend. Otherwise all other <browser> element of webext may be reloaded or go away
+    // and then we would have troubles matching targets for resources.
+    const originalBrowsingContext = this
+      .devtoolsSpawnedBrowsingContextForWebExtension
+      ? this.devtoolsSpawnedBrowsingContextForWebExtension
+      : this.originalDocShell.browsingContext;
+    const browsingContextID = originalBrowsingContext.id;
+    const innerWindowId =
+      originalBrowsingContext.currentWindowContext.innerWindowId;
+    const parentInnerWindowId =
+      originalBrowsingContext.parent?.currentWindowContext.innerWindowId;
+    // Doesn't only check `!!opener` as some iframe might have an opener
+    // if their location was loaded via `window.open(url, "iframe-name")`.
+    // So also ensure that the document is opened in a distinct tab.
+    const isPopup =
+      !!originalBrowsingContext.opener &&
+      originalBrowsingContext.browserId !=
+        originalBrowsingContext.opener.browserId;
+
+    const response = {
+      actor: this.actorID,
+      browsingContextID,
+      processID: Services.appinfo.processID,
+      // True for targets created by JSWindowActors, see constructor JSDoc.
+      followWindowGlobalLifeCycle: this.followWindowGlobalLifeCycle,
+      innerWindowId,
+      parentInnerWindowId,
+      topInnerWindowId: this.browsingContext.topWindowContext.innerWindowId,
+      isTopLevelTarget: this.isTopLevelTarget,
+      ignoreSubFrames: this.ignoreSubFrames,
+      isPopup,
+      isPrivate: this.isPrivate,
+      traits: {
+        // @backward-compat { version 64 } Exposes a new trait to help identify
+        // BrowsingContextActor's inherited actors from the client side.
+        isBrowsingContext: true,
+        // Browsing context targets can compute the isTopLevelTarget flag on the
+        // server. But other target actors don't support this yet. See Bug 1709314.
+        supportsTopLevelTargetFlag: true,
+        // Supports frame listing via `listFrames` request and `frameUpdate` events
+        // as well as frame switching via `switchToFrame` request
+        frames: true,
+        // Supports the logInPage request.
+        logInPage: true,
+        // Supports watchpoints in the server. We need to keep this trait because target
+        // actors that don't extend WindowGlobalTargetActor (Worker, ContentProcess, …)
+        // might not support watchpoints.
+        watchpoints: true,
+        // Supports back and forward navigation
+        navigation: true,
+      },
+    };
+
+    // We may try to access window while the document is closing, then accessing window
+    // throws.
+    if (!this.docShell.isBeingDestroyed()) {
+      response.title = this.title;
+      response.url = this.url;
+      response.outerWindowID = this.outerWindowID;
+    }
+
+    const actors = this._createExtraActors();
+    Object.assign(response, actors);
+
+    // The thread actor is the only actor manually created by the target actor.
+    // It is not registered in targetScopedActorFactories and therefore needs
+    // to be added here manually.
+    if (this.threadActor) {
+      Object.assign(response, {
+        threadActor: this.threadActor.actorID,
+      });
+    }
+
+    return response;
+  }
+
+  /**
+   * Called when the actor is removed from the connection.
+   *
+   * @params {Object} options
+   * @params {Boolean} options.isTargetSwitching: Set to true when this is called during
+   *         a target switch.
+   * @params {Boolean} options.isModeSwitching: Set to true true when this is called as the
+   *         result of a change to the devtools.browsertoolbox.scope pref.
+   */
+  destroy({ isTargetSwitching = false, isModeSwitching = false } = {}) {
+    // Avoid reentrancy. We will destroy the Transport when emitting "destroyed",
+    // which will force destroying all actors.
+    if (this.destroying) {
+      return;
+    }
+    this.destroying = true;
+
+    // Tell the thread actor that the window global is closed, so that it may terminate
+    // instead of resuming the debuggee script.
+    // TODO: Bug 997119: Remove this coupling with thread actor
+    if (this.threadActor) {
+      this.threadActor._parentClosed = true;
+    }
+
+    if (this._touchSimulator) {
+      this._touchSimulator.stop();
+      this._touchSimulator = null;
+    }
+
+    // Check for `docShell` availability, as it can be already gone during
+    // Firefox shutdown.
+    if (this.docShell) {
+      this._unwatchDocShell(this.docShell);
+
+      // If this target is being destroyed as part of a target switch or a mode switch,
+      // we don't need to restore the configuration (this might cause the content page to
+      // be focused again, causing issues in tests and disturbing the user when switching modes).
+      if (!isTargetSwitching && !isModeSwitching) {
+        this._restoreTargetConfiguration();
+      }
+    }
+    this._unwatchDocshells();
+
+    this._destroyThreadActor();
+
+    if (this._styleSheetsManager) {
+      this._styleSheetsManager.destroy();
+      this._styleSheetsManager = null;
+    }
+
+    // Shut down actors that belong to this target's pool.
+    if (this._targetScopedActorPool) {
+      this._targetScopedActorPool.destroy();
+      this._targetScopedActorPool = null;
+    }
+
+    // Make sure that no more workerListChanged notifications are sent.
+    if (this._workerDescriptorActorList !== null) {
+      this._workerDescriptorActorList.destroy();
+      this._workerDescriptorActorList = null;
+    }
+
+    if (this._workerDescriptorActorPool !== null) {
+      this._workerDescriptorActorPool.destroy();
+      this._workerDescriptorActorPool = null;
+    }
+
+    if (this._dbg) {
+      this._dbg.disable();
+      this._dbg = null;
+    }
+
+    // Emit a last event before calling Actor.destroy
+    // which will destroy the EventEmitter API
+    this.emit("destroyed", { isTargetSwitching, isModeSwitching });
+
+    // Destroy BaseTargetActor before nullifying docShell in case any child actor queries the window/docShell.
+    super.destroy();
+
+    this.docShell = null;
+    this._extraActors = null;
+
+    Services.obs.removeObserver(
+      this._onConsoleApiProfilerEvent,
+      "console-api-profiler"
+    );
+
+    TargetActorRegistry.unregisterTargetActor(this);
+    Resources.unwatchAllResources(this);
+  }
+
+  /**
+   * Return true if the given global is associated with this window global and should
+   * be added as a debuggee, false otherwise.
+   */
+  _shouldAddNewGlobalAsDebuggee(wrappedGlobal) {
+    // Otherwise, check if it is a WebExtension content script sandbox
+    const global = unwrapDebuggerObjectGlobal(wrappedGlobal);
+    if (!global) {
+      return false;
+    }
+
+    // Check if the global is a sdk page-mod sandbox.
+    let metadata = {};
+    let id = "";
+    try {
+      id = getInnerId(this.window);
+      metadata = Cu.getSandboxMetadata(global);
+    } catch (e) {
+      // ignore
+    }
+    if (metadata?.["inner-window-id"] && metadata["inner-window-id"] == id) {
+      return true;
+    }
+
+    return false;
+  }
+
+  _watchDocshells() {
+    // If for some unexpected reason, the actor is immediately destroyed,
+    // avoid registering leaking observer listener.
+    if (this.isDestroyed()) {
+      return;
+    }
+
+    // In child processes, we watch all docshells living in the process.
+    Services.obs.addObserver(this, "webnavigation-create");
+    Services.obs.addObserver(this, "webnavigation-destroy");
+    this._docShellsObserved = true;
+
+    // We watch for all child docshells under the current document,
+    this._progressListener.watch(this.docShell);
+
+    // And list all already existing ones.
+    this._updateChildDocShells();
+  }
+
+  _unwatchDocshells() {
+    if (this._progressListener) {
+      this._progressListener.destroy();
+      this._progressListener = null;
+      this._originalWindow = null;
+    }
+
+    // Removes the observers being set in _watchDocshells, but only
+    // if _watchDocshells has been called. The target actor may be immediately destroyed
+    // and doesn't have time to register them.
+    // (Calling removeObserver without having called addObserver throws)
+    if (this._docShellsObserved) {
+      Services.obs.removeObserver(this, "webnavigation-create");
+      Services.obs.removeObserver(this, "webnavigation-destroy");
+      this._docShellsObserved = false;
+    }
+  }
+
+  _unwatchDocShell(docShell) {
+    if (this._progressListener) {
+      this._progressListener.unwatch(docShell);
+    }
+  }
+
+  switchToFrame(request) {
+    const windowId = request.windowId;
+    let win;
+
+    try {
+      win = Services.wm.getOuterWindowWithId(windowId);
+    } catch (e) {
+      // ignore
+    }
+    if (!win) {
+      throw {
+        error: "noWindow",
+        message: "The related docshell is destroyed or not found",
+      };
+    } else if (win == this.window) {
+      return {};
+    }
+
+    // Reply first before changing the document
+    DevToolsUtils.executeSoon(() => this._changeTopLevelDocument(win));
+
+    return {};
+  }
+
+  listFrames(request) {
+    const windows = this._docShellsToWindows(this.docShells);
+    return { frames: windows };
+  }
+
+  ensureWorkerDescriptorActorList() {
+    if (this._workerDescriptorActorList === null) {
+      this._workerDescriptorActorList = new WorkerDescriptorActorList(
+        this.conn,
+        {
+          type: Ci.nsIWorkerDebugger.TYPE_DEDICATED,
+          window: this.window,
+        }
+      );
+    }
+    return this._workerDescriptorActorList;
+  }
+
+  pauseWorkersUntilAttach(shouldPause) {
+    this.ensureWorkerDescriptorActorList().workerPauser.setPauseMatching(
+      shouldPause
+    );
+  }
+
+  listWorkers(request) {
+    return this.ensureWorkerDescriptorActorList()
+      .getList()
+      .then(actors => {
+        const pool = new Pool(this.conn, "worker-targets");
+        for (const actor of actors) {
+          pool.manage(actor);
+        }
+
+        // Do not destroy the pool before transfering ownership to the newly created
+        // pool, so that we do not accidently destroy actors that are still in use.
+        if (this._workerDescriptorActorPool) {
+          this._workerDescriptorActorPool.destroy();
+        }
+
+        this._workerDescriptorActorPool = pool;
+        this._workerDescriptorActorList.onListChanged =
+          this._onWorkerDescriptorActorListChanged;
+
+        return {
+          workers: actors,
+        };
+      });
+  }
+
+  logInPage(request) {
+    const { text, category, flags } = request;
+    const scriptErrorClass = Cc["@mozilla.org/scripterror;1"];
+    const scriptError = scriptErrorClass.createInstance(Ci.nsIScriptError);
+    scriptError.initWithWindowID(
+      text,
+      null,
+      null,
+      0,
+      0,
+      flags,
+      category,
+      getInnerId(this.window)
+    );
+    Services.console.logMessage(scriptError);
+    return {};
+  }
+
+  _onWorkerDescriptorActorListChanged() {
+    this._workerDescriptorActorList.onListChanged = null;
+    this.emit("workerListChanged");
+  }
+
+  _onConsoleApiProfilerEvent(subject, topic, data) {
+    // TODO: We will receive console-api-profiler events for any browser running
+    // in the same process as this target. We should filter irrelevant events,
+    // but console-api-profiler currently doesn't emit any information to identify
+    // the origin of the event. See Bug 1731033.
+
+    // The new performance panel is not compatible with console.profile().
+    const warningFlag = 1;
+    this.logInPage({
+      text:
+        "console.profile is not compatible with the new Performance recorder. " +
+        "See https://bugzilla.mozilla.org/show_bug.cgi?id=1730896",
+      category: "console.profile unavailable",
+      flags: warningFlag,
+    });
+  }
+
+  observe(subject, topic, data) {
+    // Ignore any event that comes before/after the actor is attached.
+    // That typically happens during Firefox shutdown.
+    if (this.isDestroyed()) {
+      return;
+    }
+
+    subject.QueryInterface(Ci.nsIDocShell);
+
+    if (topic == "webnavigation-create") {
+      this._onDocShellCreated(subject);
+    } else if (topic == "webnavigation-destroy") {
+      this._onDocShellDestroy(subject);
+    }
+  }
+
+  _onDocShellCreated(docShell) {
+    // (chrome-)webnavigation-create is fired very early during docshell
+    // construction. In new root docshells within child processes, involving
+    // BrowserChild, this event is from within this call:
+    //   https://hg.mozilla.org/mozilla-central/annotate/74d7fb43bb44/dom/ipc/TabChild.cpp#l912
+    // whereas the chromeEventHandler (and most likely other stuff) is set
+    // later:
+    //   https://hg.mozilla.org/mozilla-central/annotate/74d7fb43bb44/dom/ipc/TabChild.cpp#l944
+    // So wait a tick before watching it:
+    DevToolsUtils.executeSoon(() => {
+      // Bug 1142752: sometimes, the docshell appears to be immediately
+      // destroyed, bailout early to prevent random exceptions.
+      if (docShell.isBeingDestroyed()) {
+        return;
+      }
+
+      // In child processes, we have new root docshells,
+      // let's watch them and all their child docshells.
+      if (this._isRootDocShell(docShell) && this.watchNewDocShells) {
+        this._progressListener.watch(docShell);
+      }
+      this._notifyDocShellsUpdate([docShell]);
+    });
+  }
+
+  _onDocShellDestroy(docShell) {
+    // Stop watching this docshell (the unwatch() method will check if we
+    // started watching it before).
+    this._unwatchDocShell(docShell);
+
+    const webProgress = docShell
+      .QueryInterface(Ci.nsIInterfaceRequestor)
+      .getInterface(Ci.nsIWebProgress);
+    this._notifyDocShellDestroy(webProgress);
+
+    if (webProgress.DOMWindow == this._originalWindow) {
+      // If the original top level document we connected to is removed,
+      // we try to switch to any other top level document
+      const rootDocShells = this.docShells.filter(d => {
+        // Ignore docshells without a working DOM Window.
+        // When we close firefox we have a chrome://extensions/content/dummy.xhtml
+        // which is in process of being destroyed and we might try to fallback to it.
+        // Unfortunately docshell.isBeingDestroyed() doesn't return true...
+        return d != this.docShell && this._isRootDocShell(d) && d.DOMWindow;
+      });
+      if (rootDocShells.length) {
+        const newRoot = rootDocShells[0];
+        this._originalWindow = newRoot.DOMWindow;
+        this._changeTopLevelDocument(this._originalWindow);
+      } else {
+        // If for some reason (typically during Firefox shutdown), the original
+        // document is destroyed, and there is no other top level docshell,
+        // we detach the actor to unregister all listeners and prevent any
+        // exception.
+        this.destroy();
+      }
+      return;
+    }
+
+    // If the currently targeted window global is destroyed, and we aren't on
+    // the top-level document, we have to switch to the top-level one.
+    if (
+      webProgress.DOMWindow == this.window &&
+      this.window != this._originalWindow
+    ) {
+      this._changeTopLevelDocument(this._originalWindow);
+    }
+  }
+
+  _isRootDocShell(docShell) {
+    // Should report as root docshell:
+    //  - New top level window's docshells, when using ParentProcessTargetActor against a
+    // process. It allows tracking iframes of the newly opened windows
+    // like Browser console or new browser windows.
+    //  - MozActivities or window.open frames on B2G, where a new root docshell
+    // is spawn in the child process of the app.
+    return !docShell.parent;
+  }
+
+  _docShellToWindow(docShell) {
+    const webProgress = docShell
+      .QueryInterface(Ci.nsIInterfaceRequestor)
+      .getInterface(Ci.nsIWebProgress);
+    const window = webProgress.DOMWindow;
+    const id = docShell.outerWindowID;
+    let parentID = undefined;
+    // Ignore the parent of the original document on non-e10s firefox,
+    // as we get the xul window as parent and don't care about it.
+    // Furthermore, ignore setting parentID when parent window is same as
+    // current window in order to deal with front end. e.g. toolbox will be fall
+    // into infinite loop due to recursive search with by using parent id.
+    if (
+      window.parent &&
+      window.parent != window &&
+      window != this._originalWindow
+    ) {
+      parentID = window.parent.docShell.outerWindowID;
+    }
+
+    return {
+      id,
+      parentID,
+      isTopLevel: window == this.originalWindow && this.isTopLevelTarget,
+      url: window.location.href,
+      title: window.document.title,
+    };
+  }
+
+  // Convert docShell list to windows objects list being sent to the client
+  _docShellsToWindows(docshells) {
+    return docshells
+      .filter(docShell => {
+        // Ensure docShell.document is available.
+        docShell.QueryInterface(Ci.nsIWebNavigation);
+
+        // don't include transient about:blank documents
+        if (docShell.document.isInitialDocument) {
+          return false;
+        }
+
+        return true;
+      })
+      .map(docShell => this._docShellToWindow(docShell));
+  }
+
+  _notifyDocShellsUpdate(docshells) {
+    // Only top level target uses frameUpdate in order to update the iframe dropdown.
+    // This may eventually be replaced by Target listening and target switching.
+    if (!this.isTopLevelTarget) {
+      return;
+    }
+
+    const windows = this._docShellsToWindows(docshells);
+
+    // Do not send the `frameUpdate` event if the windows array is empty.
+    if (!windows.length) {
+      return;
+    }
+
+    this.emit("frameUpdate", {
+      frames: windows,
+    });
+  }
+
+  _updateChildDocShells() {
+    this._notifyDocShellsUpdate(this.docShells);
+  }
+
+  _notifyDocShellDestroy(webProgress) {
+    // Only top level target uses frameUpdate in order to update the iframe dropdown.
+    // This may eventually be replaced by Target listening and target switching.
+    if (!this.isTopLevelTarget) {
+      return;
+    }
+
+    webProgress = webProgress.QueryInterface(Ci.nsIWebProgress);
+    const id = webProgress.DOMWindow.docShell.outerWindowID;
+    this.emit("frameUpdate", {
+      frames: [
+        {
+          id,
+          destroy: true,
+        },
+      ],
+    });
+  }
+
+  /**
+   * Creates and manages the thread actor as part of the Browsing Context Target pool.
+   * This sets up the content window for being debugged
+   */
+  _createThreadActor() {
+    this.threadActor = new ThreadActor(this, this.window);
+    this.manage(this.threadActor);
+  }
+
+  /**
+   * Exits the current thread actor and removes it from the Browsing Context Target pool.
+   * The content window is no longer being debugged after this call.
+   */
+  _destroyThreadActor() {
+    if (this.threadActor) {
+      this.threadActor.destroy();
+      this.threadActor = null;
+    }
+
+    if (this._sourcesManager) {
+      this._sourcesManager.destroy();
+      this._sourcesManager = null;
+    }
+  }
+
+  // Protocol Request Handlers
+
+  detach(request) {
+    // Destroy the actor in the next event loop in order
+    // to ensure responding to the `detach` request.
+    DevToolsUtils.executeSoon(() => {
+      this.destroy();
+    });
+
+    return {};
+  }
+
+  /**
+   * Bring the window global's window to front.
+   */
+  focus() {
+    if (this.window) {
+      this.window.focus();
+    }
+    return {};
+  }
+
+  goForward() {
+    // Wait a tick so that the response packet can be dispatched before the
+    // subsequent navigation event packet.
+    Services.tm.dispatchToMainThread(
+      DevToolsUtils.makeInfallible(() => {
+        // This won't work while the browser is shutting down and we don't really
+        // care.
+        if (Services.startup.shuttingDown) {
+          return;
+        }
+
+        this.webNavigation.goForward();
+      }, "WindowGlobalTargetActor.prototype.goForward's delayed body")
+    );
+
+    return {};
+  }
+
+  goBack() {
+    // Wait a tick so that the response packet can be dispatched before the
+    // subsequent navigation event packet.
+    Services.tm.dispatchToMainThread(
+      DevToolsUtils.makeInfallible(() => {
+        // This won't work while the browser is shutting down and we don't really
+        // care.
+        if (Services.startup.shuttingDown) {
+          return;
+        }
+
+        this.webNavigation.goBack();
+      }, "WindowGlobalTargetActor.prototype.goBack's delayed body")
+    );
+
+    return {};
+  }
+
+  /**
+   * Reload the page in this window global.
+   *
+   * @backward-compat { legacy }
+   *                  reload is preserved for third party tools. See Bug 1717837.
+   *                  DevTools should use Descriptor::reloadDescriptor instead.
+   */
+  reload(request) {
+    const force = request?.options?.force;
+    // Wait a tick so that the response packet can be dispatched before the
+    // subsequent navigation event packet.
+    Services.tm.dispatchToMainThread(
+      DevToolsUtils.makeInfallible(() => {
+        // This won't work while the browser is shutting down and we don't really
+        // care.
+        if (Services.startup.shuttingDown) {
+          return;
+        }
+
+        this.webNavigation.reload(
+          force
+            ? Ci.nsIWebNavigation.LOAD_FLAGS_BYPASS_CACHE
+            : Ci.nsIWebNavigation.LOAD_FLAGS_NONE
+        );
+      }, "WindowGlobalTargetActor.prototype.reload's delayed body")
+    );
+    return {};
+  }
+
+  /**
+   * Navigate this window global to a new location
+   */
+  navigateTo(request) {
+    // Wait a tick so that the response packet can be dispatched before the
+    // subsequent navigation event packet.
+    Services.tm.dispatchToMainThread(
+      DevToolsUtils.makeInfallible(() => {
+        this.window.location = request.url;
+      }, "WindowGlobalTargetActor.prototype.navigateTo's delayed body:" + request.url)
+    );
+    return {};
+  }
+
+  /**
+   * For browsing-context targets which can't use the watcher configuration
+   * actor (eg webextension targets), the client directly calls `reconfigure`.
+   * Once all targets support the watcher, this method can be removed.
+   */
+  reconfigure(request) {
+    const options = request.options || {};
+    return this.updateTargetConfiguration(options);
+  }
+
+  /**
+   * Apply target-specific options.
+   *
+   * This will be called by the watcher when the DevTools target-configuration
+   * is updated, or when a target is created via JSWindowActors.
+   */
+  updateTargetConfiguration(options = {}, calledFromDocumentCreation = false) {
+    if (!this.docShell) {
+      // The window global is already closed.
+      return;
+    }
+
+    let reload = false;
+    if (typeof options.touchEventsOverride !== "undefined") {
+      const enableTouchSimulator = options.touchEventsOverride === "enabled";
+
+      this.docShell.metaViewportOverride = enableTouchSimulator
+        ? Ci.nsIDocShell.META_VIEWPORT_OVERRIDE_ENABLED
+        : Ci.nsIDocShell.META_VIEWPORT_OVERRIDE_NONE;
+
+      // We want to reload the document if it's an "existing" top level target on which
+      // the touch simulator will be toggled and the user has turned the
+      // "reload on touch simulation" setting on.
+      if (
+        enableTouchSimulator !== this.touchSimulator.enabled &&
+        options.reloadOnTouchSimulationToggle === true &&
+        this.isTopLevelTarget &&
+        !calledFromDocumentCreation
+      ) {
+        reload = true;
+      }
+
+      if (enableTouchSimulator) {
+        this.touchSimulator.start();
+      } else {
+        this.touchSimulator.stop();
+      }
+    }
+
+    if (typeof options.customFormatters !== "undefined") {
+      this.customFormatters = options.customFormatters;
+    }
+
+    if (typeof options.useSimpleHighlightersForReducedMotion == "boolean") {
+      this._useSimpleHighlightersForReducedMotion =
+        options.useSimpleHighlightersForReducedMotion;
+      this.emit("use-simple-highlighters-updated");
+    }
+
+    if (!this.isTopLevelTarget) {
+      // Following DevTools target options should only apply to the top target and be
+      // propagated through the window global tree via the platform.
+      return;
+    }
+    if (typeof options.restoreFocus == "boolean") {
+      this._restoreFocus = options.restoreFocus;
+    }
+    if (typeof options.recordAllocations == "object") {
+      const actor = this._memoryActor;
+      if (options.recordAllocations == null) {
+        actor.stopRecordingAllocations();
+      } else {
+        actor.attach();
+        actor.startRecordingAllocations(options.recordAllocations);
+      }
+    }
+
+    if (reload) {
+      this.webNavigation.reload(Ci.nsIWebNavigation.LOAD_FLAGS_NONE);
+    }
+  }
+
+  get touchSimulator() {
+    if (!this._touchSimulator) {
+      this._touchSimulator = new TouchSimulator(this.chromeEventHandler);
+    }
+
+    return this._touchSimulator;
+  }
+
+  /**
+   * Opposite of the updateTargetConfiguration method, that resets document
+   * state when closing the toolbox.
+   */
+  _restoreTargetConfiguration() {
+    if (this._restoreFocus && this.browsingContext?.isActive) {
+      this.window.focus();
+    }
+  }
+
+  _changeTopLevelDocument(window) {
+    // In case of WebExtension, still using one WindowGlobalTarget instance for many document,
+    // when reloading the add-on we might not destroy the previous target and wait for the next
+    // one to come and destroy it.
+    if (this.window) {
+      // Fake a will-navigate on the previous document
+      // to let a chance to unregister it
+      this._willNavigate({
+        window: this.window,
+        newURI: window.location.href,
+        request: null,
+        isFrameSwitching: true,
+        navigationStart: Date.now(),
+      });
+
+      this._windowDestroyed(this.window, {
+        isFrozen: true,
+        isFrameSwitching: true,
+      });
+    }
+
+    // Immediately change the window as this window, if in process of unload
+    // may already be non working on the next cycle and start throwing
+    this._setWindow(window);
+
+    DevToolsUtils.executeSoon(() => {
+      // No need to do anything more if the actor is destroyed.
+      // e.g. the client has been closed and the actors destroyed in the meantime.
+      if (this.isDestroyed()) {
+        return;
+      }
+
+      // Then fake window-ready and navigate on the given document
+      this._windowReady(window, { isFrameSwitching: true });
+      DevToolsUtils.executeSoon(() => {
+        this._navigate(window, true);
+      });
+    });
+  }
+
+  _setWindow(window) {
+    // Here is the very important call where we switch the currently targeted
+    // window global (it will indirectly update this.window and many other
+    // attributes defined from docShell).
+    this.docShell = window.docShell;
+    this.emit("changed-toplevel-document");
+    this.emit("frameUpdate", {
+      selected: this.outerWindowID,
+    });
+  }
+
+  /**
+   * Handle location changes, by clearing the previous debuggees and enabling
+   * debugging, which may have been disabled temporarily by the
+   * DebuggerProgressListener.
+   */
+  _windowReady(window, { isFrameSwitching, isBFCache } = {}) {
+    if (this.ignoreSubFrames) {
+      return;
+    }
+    const isTopLevel = window == this.window;
+
+    // We just reset iframe list on WillNavigate, so we now list all existing
+    // frames when we load a new document in the original window
+    if (window == this._originalWindow && !isFrameSwitching) {
+      this._updateChildDocShells();
+    }
+
+    // If this follows WindowGlobal lifecycle, a new Target actor will be spawn for the top level
+    // target document. Only notify about in-process iframes.
+    // Note that OOP iframes won't emit window-ready and will also have their dedicated target.
+    // Also, we allow window-ready to be fired for iframe switching of top level documents,
+    // otherwise the iframe dropdown no longer works with server side targets.
+    if (this.followWindowGlobalLifeCycle && isTopLevel && !isFrameSwitching) {
+      return;
+    }
+
+    this.emit("window-ready", {
+      window,
+      isTopLevel,
+      isBFCache,
+      id: getWindowID(window),
+      isFrameSwitching,
+    });
+  }
+
+  _windowDestroyed(
+    window,
+    { id = null, isFrozen = false, isFrameSwitching = false }
+  ) {
+    if (this.ignoreSubFrames) {
+      return;
+    }
+    const isTopLevel = window == this.window;
+
+    // If this follows WindowGlobal lifecycle, this target will be destroyed, alongside its top level document.
+    // Only notify about in-process iframes.
+    // Note that OOP iframes won't emit window-ready and will also have their dedicated target.
+    // Also, we allow window-destroyed to be fired for iframe switching of top level documents,
+    // otherwise the iframe dropdown no longer works with server side targets.
+    if (this.followWindowGlobalLifeCycle && isTopLevel && !isFrameSwitching) {
+      return;
+    }
+
+    this.emit("window-destroyed", {
+      window,
+      isTopLevel,
+      id: id || getWindowID(window),
+      isFrozen,
+    });
+  }
+
+  /**
+   * Start notifying server and client about a new document being loaded in the
+   * currently targeted window global.
+   */
+  _willNavigate({
+    window,
+    newURI,
+    request,
+    isFrameSwitching = false,
+    navigationStart,
+  }) {
+    if (this.ignoreSubFrames) {
+      return;
+    }
+    let isTopLevel = window == this.window;
+
+    let reset = false;
+    if (window == this._originalWindow && !isFrameSwitching) {
+      // If the top level document changes and we are targeting an iframe, we
+      // need to reset to the upcoming new top level document. But for this
+      // will-navigate event, we will dispatch on the old window. (The inspector
+      // codebase expect to receive will-navigate for the currently displayed
+      // document in order to cleanup the markup view)
+      if (this.window != this._originalWindow) {
+        reset = true;
+        window = this.window;
+        isTopLevel = true;
+      }
+    }
+
+    // will-navigate event needs to be dispatched synchronously, by calling the
+    // listeners in the order or registration. This event fires once navigation
+    // starts, (all pending user prompts are dealt with), but before the first
+    // request starts.
+    this.emit("will-navigate", {
+      window,
+      isTopLevel,
+      newURI,
+      request,
+      navigationStart,
+      isFrameSwitching,
+    });
+
+    // We don't do anything for inner frames here.
+    // (we will only update thread actor on window-ready)
+    if (!isTopLevel) {
+      return;
+    }
+
+    // When the actor acts as a WindowGlobalTarget, will-navigate won't fired.
+    // Instead we will receive a new top level target with isTargetSwitching=true.
+    if (!this.followWindowGlobalLifeCycle) {
+      this.emit("tabNavigated", {
+        url: newURI,
+        state: "start",
+        isFrameSwitching,
+      });
+    }
+
+    if (reset) {
+      this._setWindow(this._originalWindow);
+    }
+  }
+
+  /**
+   * Notify server and client about a new document done loading in the current
+   * targeted window global.
+   */
+  _navigate(window, isFrameSwitching = false) {
+    if (this.ignoreSubFrames) {
+      return;
+    }
+    const isTopLevel = window == this.window;
+
+    // navigate event needs to be dispatched synchronously,
+    // by calling the listeners in the order or registration.
+    // This event is fired once the document is loaded,
+    // after the load event, it's document ready-state is 'complete'.
+    this.emit("navigate", {
+      window,
+      isTopLevel,
+    });
+
+    // We don't do anything for inner frames here.
+    // (we will only update thread actor on window-ready)
+    if (!isTopLevel) {
+      return;
+    }
+
+    // We may still significate when the document is done loading, via navigate.
+    // But as we no longer fire the "will-navigate", may be it is better to find
+    // other ways to get to our means.
+    // Listening to "navigate" is misleading as the document may already be loaded
+    // if we just opened the DevTools. So it is better to use "watch" pattern
+    // and instead have the actor either emit immediately resources as they are
+    // already available, or later on as the load progresses.
+    if (this.followWindowGlobalLifeCycle) {
+      return;
+    }
+
+    this.emit("tabNavigated", {
+      url: this.url,
+      title: this.title,
+      state: "stop",
+      isFrameSwitching,
+    });
+  }
+
+  removeActorByName(name) {
+    if (name in this._extraActors) {
+      const actor = this._extraActors[name];
+      if (this._targetScopedActorPool.has(actor)) {
+        this._targetScopedActorPool.removeActor(actor);
+      }
+      delete this._extraActors[name];
+    }
+  }
+}
+
+exports.WindowGlobalTargetActor = WindowGlobalTargetActor;
+
+class DebuggerProgressListener {
+  /**
+   * The DebuggerProgressListener class is an nsIWebProgressListener which
+   * handles onStateChange events for the targeted window global. If the user
+   * tries to navigate away from a paused page, the listener makes sure that the
+   * debuggee is resumed before the navigation begins.
+   *
+   * @param WindowGlobalTargetActor targetActor
+   *        The window global target actor associated with this listener.
+   */
+  constructor(targetActor) {
+    this._targetActor = targetActor;
+    this._onWindowCreated = this.onWindowCreated.bind(this);
+    this._onWindowHidden = this.onWindowHidden.bind(this);
+
+    // Watch for windows destroyed (global observer that will need filtering)
+    Services.obs.addObserver(this, "inner-window-destroyed");
+
+    // XXX: for now we maintain the list of windows we know about in this instance
+    // so that we can discriminate windows we care about when observing
+    // inner-window-destroyed events. Bug 1016952 would remove the need for this.
+    this._knownWindowIDs = new Map();
+
+    this._watchedDocShells = new WeakSet();
+  }
+
+  QueryInterface = ChromeUtils.generateQI([
+    "nsIWebProgressListener",
+    "nsISupportsWeakReference",
+  ]);
+
+  destroy() {
+    Services.obs.removeObserver(this, "inner-window-destroyed");
+    this._knownWindowIDs.clear();
+    this._knownWindowIDs = null;
+  }
+
+  watch(docShell) {
+    // Add the docshell to the watched set. We're actually adding the window,
+    // because docShell objects are not wrappercached and would be rejected
+    // by the WeakSet.
+    const docShellWindow = docShell.domWindow;
+    this._watchedDocShells.add(docShellWindow);
+
+    const webProgress = docShell
+      .QueryInterface(Ci.nsIInterfaceRequestor)
+      .getInterface(Ci.nsIWebProgress);
+    webProgress.addProgressListener(
+      this,
+      Ci.nsIWebProgress.NOTIFY_STATE_WINDOW |
+        Ci.nsIWebProgress.NOTIFY_STATE_DOCUMENT
+    );
+
+    const handler = getDocShellChromeEventHandler(docShell);
+    handler.addEventListener("DOMWindowCreated", this._onWindowCreated, true);
+    handler.addEventListener("pageshow", this._onWindowCreated, true);
+    handler.addEventListener("pagehide", this._onWindowHidden, true);
+
+    // Dispatch the _windowReady event on the targetActor for pre-existing windows
+    const windows = this._targetActor.ignoreSubFrames
+      ? [docShellWindow]
+      : this._getWindowsInDocShell(docShell);
+    for (const win of windows) {
+      this._targetActor._windowReady(win);
+      this._knownWindowIDs.set(getWindowID(win), win);
+    }
+
+    // The `watchedByDevTools` enables gecko behavior tied to this flag, such as:
+    //  - reporting the contents of HTML loaded in the docshells,
+    //  - or capturing stacks for the network monitor.
+    //
+    // This flag is also set in frame-helper but in the case of the browser toolbox, we
+    // don't have the watcher enabled by default yet, and as a result we need to set it
+    // here for the parent process window global.
+    // This should be removed as part of Bug 1709529.
+    if (this._targetActor.typeName === "parentProcessTarget") {
+      docShell.browsingContext.watchedByDevTools = true;
+    }
+    // Immediately enable CSS error reports on new top level docshells, if this was already enabled.
+    // This is specific to MBT and WebExtension targets (so the isRootActor check).
+    if (
+      this._targetActor.isRootActor &&
+      this._targetActor.docShell.cssErrorReportingEnabled
+    ) {
+      docShell.cssErrorReportingEnabled = true;
+    }
+  }
+
+  unwatch(docShell) {
+    const docShellWindow = docShell.domWindow;
+    if (!this._watchedDocShells.has(docShellWindow)) {
+      return;
+    }
+    this._watchedDocShells.delete(docShellWindow);
+
+    const webProgress = docShell
+      .QueryInterface(Ci.nsIInterfaceRequestor)
+      .getInterface(Ci.nsIWebProgress);
+    // During process shutdown, the docshell may already be cleaned up and throw
+    try {
+      webProgress.removeProgressListener(this);
+    } catch (e) {
+      // ignore
+    }
+
+    const handler = getDocShellChromeEventHandler(docShell);
+    handler.removeEventListener(
+      "DOMWindowCreated",
+      this._onWindowCreated,
+      true
+    );
+    handler.removeEventListener("pageshow", this._onWindowCreated, true);
+    handler.removeEventListener("pagehide", this._onWindowHidden, true);
+
+    const windows = this._targetActor.ignoreSubFrames
+      ? [docShellWindow]
+      : this._getWindowsInDocShell(docShell);
+    for (const win of windows) {
+      this._knownWindowIDs.delete(getWindowID(win));
+    }
+
+    // We only reset it for parent process target actor as the flag should be set in parent
+    // process, and thus is set elsewhere for other type of BrowsingContextActor.
+    if (this._targetActor.typeName === "parentProcessTarget") {
+      docShell.browsingContext.watchedByDevTools = false;
+    }
+  }
+
+  _getWindowsInDocShell(docShell) {
+    return getChildDocShells(docShell).map(d => {
+      return d.domWindow;
+    });
+  }
+
+  onWindowCreated = DevToolsUtils.makeInfallible(function (evt) {
+    if (this._targetActor.isDestroyed()) {
+      return;
+    }
+
+    // If we're in a frame swap (which occurs when toggling RDM, for example), then we can
+    // ignore this event, as the window never really went anywhere for our purposes.
+    if (evt.inFrameSwap) {
+      return;
+    }
+
+    const window = evt.target.defaultView;
+    if (!window) {
+      // Some old UIs might emit unrelated events called pageshow/pagehide on
+      // elements which are not documents. Bail in this case. See Bug 1669666.
+      return;
+    }
+
+    const innerID = getWindowID(window);
+
+    // This handler is called for two events: "DOMWindowCreated" and "pageshow".
+    // Bail out if we already processed this window.
+    if (this._knownWindowIDs.has(innerID)) {
+      return;
+    }
+    this._knownWindowIDs.set(innerID, window);
+
+    // For a regular page navigation, "DOMWindowCreated" is fired before
+    // "pageshow". If the current event is "pageshow" but we have not processed
+    // the window yet, it means this is a BF cache navigation. In theory,
+    // `event.persisted` should be set for BF cache navigation events, but it is
+    // not always available, so we fallback on checking if "pageshow" is the
+    // first event received for a given window (see Bug 1378133).
+    const isBFCache = evt.type == "pageshow";
+
+    this._targetActor._windowReady(window, { isBFCache });
+  }, "DebuggerProgressListener.prototype.onWindowCreated");
+
+  onWindowHidden = DevToolsUtils.makeInfallible(function (evt) {
+    if (this._targetActor.isDestroyed()) {
+      return;
+    }
+
+    // If we're in a frame swap (which occurs when toggling RDM, for example), then we can
+    // ignore this event, as the window isn't really going anywhere for our purposes.
+    if (evt.inFrameSwap) {
+      return;
+    }
+
+    // Only act as if the window has been destroyed if the 'pagehide' event
+    // was sent for a persisted window (persisted is set when the page is put
+    // and frozen in the bfcache). If the page isn't persisted, the observer's
+    // inner-window-destroyed event will handle it.
+    if (!evt.persisted) {
+      return;
+    }
+
+    const window = evt.target.defaultView;
+    if (!window) {
+      // Some old UIs might emit unrelated events called pageshow/pagehide on
+      // elements which are not documents. Bail in this case. See Bug 1669666.
+      return;
+    }
+
+    this._targetActor._windowDestroyed(window, { isFrozen: true });
+    this._knownWindowIDs.delete(getWindowID(window));
+  }, "DebuggerProgressListener.prototype.onWindowHidden");
+
+  observe = DevToolsUtils.makeInfallible(function (subject, topic) {
+    if (this._targetActor.isDestroyed()) {
+      return;
+    }
+
+    // Because this observer will be called for all inner-window-destroyed in
+    // the application, we need to filter out events for windows we are not
+    // watching
+    const innerID = subject.QueryInterface(Ci.nsISupportsPRUint64).data;
+    const window = this._knownWindowIDs.get(innerID);
+    if (window) {
+      this._knownWindowIDs.delete(innerID);
+      this._targetActor._windowDestroyed(window, { id: innerID });
+    }
+
+    // Bug 1598364: when debugging browser.xhtml from the Browser Toolbox
+    // the DOMWindowCreated/pageshow/pagehide event listeners have to be
+    // re-registered against the next document when we reload browser.html
+    // (or navigate to another doc).
+    // That's because we registered the listener on docShell.domWindow as
+    // top level windows don't have a chromeEventHandler.
+    if (
+      this._watchedDocShells.has(window) &&
+      !window.docShell.chromeEventHandler
+    ) {
+      // First cleanup all the existing listeners
+      this.unwatch(window.docShell);
+      // Re-register new ones. The docShell is already referencing the new document.
+      this.watch(window.docShell);
+    }
+  }, "DebuggerProgressListener.prototype.observe");
+
+  onStateChange = DevToolsUtils.makeInfallible(function (
+    progress,
+    request,
+    flag,
+    status
+  ) {
+    if (this._targetActor.isDestroyed()) {
+      return;
+    }
+    progress.QueryInterface(Ci.nsIDocShell);
+    if (progress.isBeingDestroyed()) {
+      return;
+    }
+
+    const isStart = flag & Ci.nsIWebProgressListener.STATE_START;
+    const isStop = flag & Ci.nsIWebProgressListener.STATE_STOP;
+    const isDocument = flag & Ci.nsIWebProgressListener.STATE_IS_DOCUMENT;
+    const isWindow = flag & Ci.nsIWebProgressListener.STATE_IS_WINDOW;
+
+    // Ideally, we would fetch navigationStart from window.performance.timing.navigationStart
+    // but as WindowGlobal isn't instantiated yet we don't have access to it.
+    // This is ultimately handed over to DocumentEventListener, which uses this.
+    // See its comment about WILL_NAVIGATE_TIME_SHIFT for more details about the related workaround.
+    const navigationStart = Date.now();
+
+    // Catch any iframe location change
+    if (isDocument && isStop) {
+      // Watch document stop to ensure having the new iframe url.
+      this._targetActor._notifyDocShellsUpdate([progress]);
+    }
+
+    const window = progress.DOMWindow;
+    if (isDocument && isStart) {
+      // One of the earliest events that tells us a new URI
+      // is being loaded in this window.
+      const newURI = request instanceof Ci.nsIChannel ? request.URI.spec : null;
+      this._targetActor._willNavigate({
+        window,
+        newURI,
+        request,
+        isFrameSwitching: false,
+        navigationStart,
+      });
+    }
+    if (isWindow && isStop) {
+      // Don't dispatch "navigate" event just yet when there is a redirect to
+      // about:neterror page.
+      // Navigating to about:neterror will make `status` be something else than NS_OK.
+      // But for some error like NS_BINDING_ABORTED we don't want to emit any `navigate`
+      // event as the page load has been cancelled and the related page document is going
+      // to be a dead wrapper.
+      if (
+        request.status != Cr.NS_OK &&
+        request.status != Cr.NS_BINDING_ABORTED
+      ) {
+        // Instead, listen for DOMContentLoaded as about:neterror is loaded
+        // with LOAD_BACKGROUND flags and never dispatches load event.
+        // That may be the same reason why there is no onStateChange event
+        // for about:neterror loads.
+        const handler = getDocShellChromeEventHandler(progress);
+        const onLoad = evt => {
+          // Ignore events from iframes
+          if (evt.target === window.document) {
+            handler.removeEventListener("DOMContentLoaded", onLoad, true);
+            this._targetActor._navigate(window);
+          }
+        };
+        handler.addEventListener("DOMContentLoaded", onLoad, true);
+      } else {
+        // Somewhat equivalent of load event.
+        // (window.document.readyState == complete)
+        this._targetActor._navigate(window);
+      }
+    }
+  },
+  "DebuggerProgressListener.prototype.onStateChange");
+}
diff --git a/devtools/server/actors/targets/worker.js b/devtools/server/actors/targets/worker.js
new file mode 100644
index 0000000000..fb523b43c5
--- /dev/null
+++ b/devtools/server/actors/targets/worker.js
@@ -0,0 +1,134 @@
+/* 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";
+
+const {
+  workerTargetSpec,
+} = require("resource://devtools/shared/specs/targets/worker.js");
+
+const {
+  WebConsoleActor,
+} = require("resource://devtools/server/actors/webconsole.js");
+const { ThreadActor } = require("resource://devtools/server/actors/thread.js");
+const { TracerActor } = require("resource://devtools/server/actors/tracer.js");
+
+const Targets = require("resource://devtools/server/actors/targets/index.js");
+
+const makeDebuggerUtil = require("resource://devtools/server/actors/utils/make-debugger.js");
+const {
+  SourcesManager,
+} = require("resource://devtools/server/actors/utils/sources-manager.js");
+
+const {
+  BaseTargetActor,
+} = require("resource://devtools/server/actors/targets/base-target-actor.js");
+
+class WorkerTargetActor extends BaseTargetActor {
+  /**
+   * Target actor for a worker in the content process.
+   *
+   * @param {DevToolsServerConnection} conn: The connection to the client.
+   * @param {WorkerGlobalScope} workerGlobal: The worker global.
+   * @param {Object} workerDebuggerData: The worker debugger information
+   * @param {String} workerDebuggerData.id: The worker debugger id
+   * @param {String} workerDebuggerData.url: The worker debugger url
+   * @param {String} workerDebuggerData.type: The worker debugger type
+   * @param {Boolean} workerDebuggerData.workerConsoleApiMessagesDispatchedToMainThread:
+   *                  Value of the dom.worker.console.dispatch_events_to_main_thread pref
+   * @param {Object} sessionContext: The Session Context to help know what is debugged.
+   *                                 See devtools/server/actors/watcher/session-context.js
+   */
+  constructor(conn, workerGlobal, workerDebuggerData, sessionContext) {
+    super(conn, Targets.TYPES.WORKER, workerTargetSpec);
+
+    // workerGlobal is needed by the console actor for evaluations.
+    this.workerGlobal = workerGlobal;
+    this.sessionContext = sessionContext;
+
+    this._workerDebuggerData = workerDebuggerData;
+    this._sourcesManager = null;
+    this.workerConsoleApiMessagesDispatchedToMainThread =
+      workerDebuggerData.workerConsoleApiMessagesDispatchedToMainThread;
+
+    this.makeDebugger = makeDebuggerUtil.bind(null, {
+      findDebuggees: () => {
+        return [workerGlobal];
+      },
+      shouldAddNewGlobalAsDebuggee: () => true,
+    });
+
+    // needed by the console actor
+    this.threadActor = new ThreadActor(this, this.workerGlobal);
+
+    // needed by the thread actor to communicate with the console when evaluating logpoints.
+    this._consoleActor = new WebConsoleActor(this.conn, this);
+
+    this.tracerActor = new TracerActor(this.conn, this);
+
+    this.manage(this.threadActor);
+    this.manage(this._consoleActor);
+    this.manage(this.tracerActor);
+  }
+
+  // Expose the worker URL to the thread actor.
+  // so that it can easily know what is the base URL of all worker scripts.
+  get workerUrl() {
+    return this._workerDebuggerData.url;
+  }
+
+  form() {
+    return {
+      actor: this.actorID,
+
+      consoleActor: this._consoleActor?.actorID,
+      threadActor: this.threadActor?.actorID,
+      tracerActor: this.tracerActor?.actorID,
+
+      id: this._workerDebuggerData.id,
+      type: this._workerDebuggerData.type,
+      url: this._workerDebuggerData.url,
+      traits: {
+        // See trait description in browsing-context.js
+        supportsTopLevelTargetFlag: false,
+      },
+    };
+  }
+
+  get dbg() {
+    if (!this._dbg) {
+      this._dbg = this.makeDebugger();
+    }
+    return this._dbg;
+  }
+
+  get sourcesManager() {
+    if (this._sourcesManager === null) {
+      this._sourcesManager = new SourcesManager(this.threadActor);
+    }
+
+    return this._sourcesManager;
+  }
+
+  // This is called from the ThreadActor#onAttach method
+  onThreadAttached() {
+    // This isn't an RDP event and is only listened to from startup/worker.js.
+    this.emit("worker-thread-attached");
+  }
+
+  destroy() {
+    super.destroy();
+
+    if (this._sourcesManager) {
+      this._sourcesManager.destroy();
+      this._sourcesManager = null;
+    }
+
+    this.workerGlobal = null;
+    this._dbg = null;
+    this._consoleActor = null;
+    this.threadActor = null;
+  }
+}
+exports.WorkerTargetActor = WorkerTargetActor;