Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 689 insertions, 0 deletions

diff --git a/devtools/server/connectors/js-window-actor/DevToolsFrameChild.sys.mjs b/devtools/server/connectors/js-window-actor/DevToolsFrameChild.sys.mjs
new file mode 100644
index 0000000000..c7d5bd0718
--- /dev/null
+++ b/devtools/server/connectors/js-window-actor/DevToolsFrameChild.sys.mjs
@@ -0,0 +1,689 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+import { EventEmitter } from "resource://gre/modules/EventEmitter.sys.mjs";
+import * as Loader from "resource://devtools/shared/loader/Loader.sys.mjs";
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
+
+const lazy = {};
+ChromeUtils.defineESModuleGetters(lazy, {
+  isWindowGlobalPartOfContext:
+    "resource://devtools/server/actors/watcher/browsing-context-helpers.sys.mjs",
+  releaseDistinctSystemPrincipalLoader:
+    "resource://devtools/shared/loader/DistinctSystemPrincipalLoader.sys.mjs",
+  TargetActorRegistry:
+    "resource://devtools/server/actors/targets/target-actor-registry.sys.mjs",
+  useDistinctSystemPrincipalLoader:
+    "resource://devtools/shared/loader/DistinctSystemPrincipalLoader.sys.mjs",
+  WindowGlobalLogger:
+    "resource://devtools/server/connectors/js-window-actor/WindowGlobalLogger.sys.mjs",
+});
+
+const isEveryFrameTargetEnabled = Services.prefs.getBoolPref(
+  "devtools.every-frame-target.enabled",
+  false
+);
+
+// Name of the attribute into which we save data in `sharedData` object.
+const SHARED_DATA_KEY_NAME = "DevTools:watchedPerWatcher";
+
+// If true, log info about WindowGlobal's being created.
+const DEBUG = false;
+function logWindowGlobal(windowGlobal, message) {
+  if (!DEBUG) {
+    return;
+  }
+  lazy.WindowGlobalLogger.logWindowGlobal(windowGlobal, message);
+}
+
+export class DevToolsFrameChild extends JSWindowActorChild {
+  constructor() {
+    super();
+
+    // The map is indexed by the Watcher Actor ID.
+    // The values are objects containing the following properties:
+    // - connection: the DevToolsServerConnection itself
+    // - actor: the WindowGlobalTargetActor instance
+    this._connections = new Map();
+
+    EventEmitter.decorate(this);
+
+    // Set the following preference on the constructor, so that we can easily
+    // toggle these preferences on and off from tests and have the new value being picked up.
+
+    // bfcache-in-parent changes significantly how navigation behaves.
+    // We may start reusing previously existing WindowGlobal and so reuse
+    // previous set of JSWindowActor pairs (i.e. DevToolsFrameParent/DevToolsFrameChild).
+    // When enabled, regular navigations may also change and spawn new BrowsingContexts.
+    // If the page we navigate from supports being stored in bfcache,
+    // the navigation will use a new BrowsingContext. And so force spawning
+    // a new top-level target.
+    XPCOMUtils.defineLazyGetter(
+      this,
+      "isBfcacheInParentEnabled",
+      () =>
+        Services.appinfo.sessionHistoryInParent &&
+        Services.prefs.getBoolPref("fission.bfcacheInParent", false)
+    );
+  }
+
+  /**
+   * Try to instantiate new target actors for the current WindowGlobal, and that,
+   * for all the currently registered Watcher actors.
+   *
+   * Read the `sharedData` to get metadata about all registered watcher actors.
+   * If these watcher actors are interested in the current WindowGlobal,
+   * instantiate a new dedicated target actor for each of the watchers.
+   *
+   * @param Object options
+   * @param Boolean options.isBFCache
+   *        True, if the request to instantiate a new target comes from a bfcache navigation.
+   *        i.e. when we receive a pageshow event with persisted=true.
+   *        This will be true regardless of bfcacheInParent being enabled or disabled.
+   * @param Boolean options.ignoreIfExisting
+   *        By default to false. If true is passed, we avoid instantiating a target actor
+   *        if one already exists for this windowGlobal.
+   */
+  instantiate({ isBFCache = false, ignoreIfExisting = false } = {}) {
+    const { sharedData } = Services.cpmm;
+    const sessionDataByWatcherActor = sharedData.get(SHARED_DATA_KEY_NAME);
+    if (!sessionDataByWatcherActor) {
+      throw new Error(
+        "Request to instantiate the target(s) for the BrowsingContext, but `sharedData` is empty about watched targets"
+      );
+    }
+
+    // Create one Target actor for each prefix/client which listen to frames
+    for (const [watcherActorID, sessionData] of sessionDataByWatcherActor) {
+      const { connectionPrefix, sessionContext } = sessionData;
+      // For bfcache navigations, we only create new targets when bfcacheInParent is enabled,
+      // as this would be the only case where new DocShells will be created. This requires us to spawn a
+      // new WindowGlobalTargetActor as one such actor is bound to a unique DocShell.
+      const forceAcceptTopLevelTarget =
+        isBFCache && this.isBfcacheInParentEnabled;
+      if (
+        sessionData.targets?.includes("frame") &&
+        lazy.isWindowGlobalPartOfContext(this.manager, sessionContext, {
+          forceAcceptTopLevelTarget,
+        })
+      ) {
+        // If this was triggered because of a navigation, we want to retrieve the existing
+        // target we were debugging so we can destroy it before creating the new target.
+        // This is important because we had cases where the destruction of an old target
+        // was unsetting a flag on the **new** target document, breaking the toolbox (See Bug 1721398).
+
+        // We're checking for an existing target given a watcherActorID + browserId + browsingContext
+        // Note that a target switch might create a new browsing context, so we wouldn't
+        // retrieve the existing target here. We are okay with this as:
+        // - this shouldn't happen much
+        // - in such case we weren't seeing the issue of Bug 1721398 (the old target can't access the new document)
+        const existingTarget = this._findTargetActor({
+          watcherActorID,
+          sessionContext,
+          browsingContextId: this.manager.browsingContext.id,
+        });
+
+        // See comment in handleEvent(DOMDocElementInserted) to know why we try to
+        // create targets if none already exists
+        if (existingTarget && ignoreIfExisting) {
+          continue;
+        }
+
+        // Bail if there is already an existing WindowGlobalTargetActor which wasn't
+        // created from a JSWIndowActor.
+        // This means we are reloading or navigating (same-process) a Target
+        // which has not been created using the Watcher, but from the client (most likely
+        // the initial target of a local-tab toolbox).
+        // However, we force overriding the first message manager based target in case of
+        // BFCache navigations.
+        if (
+          existingTarget &&
+          !existingTarget.createdFromJsWindowActor &&
+          !isBFCache
+        ) {
+          continue;
+        }
+
+        // If we decide to instantiate a new target and there was one before,
+        // first destroy the previous one.
+        // Otherwise its destroy sequence will be executed *after* the new one
+        // is being initialized and may easily revert changes made against platform API.
+        // (typically toggle platform boolean attributes back to default…)
+        if (existingTarget) {
+          existingTarget.destroy({ isTargetSwitching: true });
+        }
+
+        this._createTargetActor({
+          watcherActorID,
+          parentConnectionPrefix: connectionPrefix,
+          sessionData,
+          isDocumentCreation: true,
+        });
+      }
+    }
+  }
+
+  /**
+   * Instantiate a new WindowGlobalTarget for the given connection.
+   *
+   * @param Object options
+   * @param String options.watcherActorID
+   *        The ID of the WatcherActor who requested to observe and create these target actors.
+   * @param String options.parentConnectionPrefix
+   *        The prefix of the DevToolsServerConnection of the Watcher Actor.
+   *        This is used to compute a unique ID for the target actor.
+   * @param Object options.sessionData
+   *        All data managed by the Watcher Actor and WatcherRegistry.jsm, containing
+   *        target types, resources types to be listened as well as breakpoints and any
+   *        other data meant to be shared across processes and threads.
+   * @param Boolean options.isDocumentCreation
+   *        Set to true if the function is called from `instantiate`, i.e. when we're
+   *        handling a new document being created.
+   * @param Boolean options.fromInstantiateAlreadyAvailable
+   *        Set to true if the function is called from handling `DevToolsFrameParent:instantiate-already-available`
+   *        query.
+   */
+  _createTargetActor({
+    watcherActorID,
+    parentConnectionPrefix,
+    sessionData,
+    isDocumentCreation,
+    fromInstantiateAlreadyAvailable,
+  }) {
+    if (this._connections.get(watcherActorID)) {
+      // If this function is called as a result of a `DevToolsFrameParent:instantiate-already-available`
+      // message, we might have a legitimate race condition:
+      // In frame-helper, we want to create the initial targets for a given browser element.
+      // It might happen that the `DevToolsFrameParent:instantiate-already-available` is
+      // aborted if the page navigates (and the document is destroyed) while the query is still pending.
+      // In such case, frame-helper will try to send a new message. In the meantime,
+      // the DevToolsFrameChild `DOMWindowCreated` handler may already have been called and
+      // the new target already created.
+      // We don't want to throw in such case, as our end-goal, having a target for the document,
+      // is achieved.
+      if (fromInstantiateAlreadyAvailable) {
+        return;
+      }
+      throw new Error(
+        "DevToolsFrameChild _createTargetActor was called more than once" +
+          ` for the same Watcher (Actor ID: "${watcherActorID}")`
+      );
+    }
+
+    // Compute a unique prefix, just for this WindowGlobal,
+    // which will be used to create a JSWindowActorTransport pair between content and parent processes.
+    // This is slightly hacky as we typicaly compute Prefix and Actor ID via `DevToolsServerConnection.allocID()`,
+    // but here, we can't have access to any DevTools connection as we are really early in the content process startup
+    // XXX: WindowGlobal's innerWindowId should be unique across processes, I think. So that should be safe?
+    // (this.manager == WindowGlobalChild interface)
+    const forwardingPrefix =
+      parentConnectionPrefix + "windowGlobal" + this.manager.innerWindowId;
+
+    logWindowGlobal(
+      this.manager,
+      "Instantiate WindowGlobalTarget with prefix: " + forwardingPrefix
+    );
+
+    const { connection, targetActor } = this._createConnectionAndActor(
+      forwardingPrefix,
+      sessionData
+    );
+    const form = targetActor.form();
+    // Ensure unregistering and destroying the related DevToolsServerConnection+Transport
+    // on both content and parent process JSWindowActors.
+    targetActor.once("destroyed", options => {
+      // This will destroy the content process one
+      this._destroyTargetActor(watcherActorID, options);
+      // And this will destroy the parent process one
+      try {
+        this.sendAsyncMessage("DevToolsFrameChild:destroy", {
+          actors: [
+            {
+              watcherActorID,
+              form,
+            },
+          ],
+          options,
+        });
+      } catch (e) {
+        // Ignore exception when the JSWindowActorChild has already been destroyed.
+        // We often try to emit this message while the WindowGlobal is in the process of being
+        // destroyed. We eagerly destroy the target actor during reloads,
+        // just before the WindowGlobal starts destroying, but sendAsyncMessage
+        // doesn't have time to complete and throws.
+        if (
+          !e.message.includes("JSWindowActorChild cannot send at the moment")
+        ) {
+          throw e;
+        }
+      }
+    });
+    this._connections.set(watcherActorID, {
+      connection,
+      actor: targetActor,
+    });
+
+    // Immediately queue a message for the parent process,
+    // in order to ensure that the JSWindowActorTransport is instantiated
+    // before any packet is sent from the content process.
+    // As the order of messages is guaranteed to be delivered in the order they
+    // were queued, we don't have to wait for anything around this sendAsyncMessage call.
+    // In theory, the WindowGlobalTargetActor may emit events in its constructor.
+    // If it does, such RDP packets may be lost.
+    // The important point here is to send this message before processing the sessionData,
+    // which will start the Watcher and start emitting resources on the target actor.
+    this.sendAsyncMessage("DevToolsFrameChild:connectFromContent", {
+      watcherActorID,
+      forwardingPrefix,
+      actor: targetActor.form(),
+    });
+
+    // Pass initialization data to the target actor
+    for (const type in sessionData) {
+      // `sessionData` will also contain `browserId` as well as entries with empty arrays,
+      // which shouldn't be processed.
+      const entries = sessionData[type];
+      if (!Array.isArray(entries) || !entries.length) {
+        continue;
+      }
+      targetActor.addSessionDataEntry(type, entries, isDocumentCreation);
+    }
+  }
+
+  /**
+   * @param {string} watcherActorID
+   * @param {object} options
+   * @param {boolean} options.isModeSwitching
+   *        true when this is called as the result of a change to the devtools.browsertoolbox.scope pref
+   */
+  _destroyTargetActor(watcherActorID, options) {
+    const connectionInfo = this._connections.get(watcherActorID);
+    // This connection has already been cleaned?
+    if (!connectionInfo) {
+      throw new Error(
+        `Trying to destroy a target actor that doesn't exists, or has already been destroyed. Watcher Actor ID:${watcherActorID}`
+      );
+    }
+    connectionInfo.connection.close(options);
+    this._connections.delete(watcherActorID);
+    if (this._connections.size == 0) {
+      this.didDestroy(options);
+    }
+  }
+
+  _createConnectionAndActor(forwardingPrefix, sessionData) {
+    this.useCustomLoader = this.document.nodePrincipal.isSystemPrincipal;
+
+    if (!this.loader) {
+      // When debugging chrome pages, use a new dedicated loader, using a distinct chrome compartment.
+      this.loader = this.useCustomLoader
+        ? lazy.useDistinctSystemPrincipalLoader(this)
+        : Loader;
+    }
+    const { DevToolsServer } = this.loader.require(
+      "resource://devtools/server/devtools-server.js"
+    );
+
+    const { WindowGlobalTargetActor } = this.loader.require(
+      "resource://devtools/server/actors/targets/window-global.js"
+    );
+
+    DevToolsServer.init();
+
+    // We want a special server without any root actor and only target-scoped actors.
+    // We are going to spawn a WindowGlobalTargetActor instance in the next few lines,
+    // it is going to act like a root actor without being one.
+    DevToolsServer.registerActors({ target: true });
+
+    const connection = DevToolsServer.connectToParentWindowActor(
+      this,
+      forwardingPrefix
+    );
+
+    // In the case of the browser toolbox, tab's BrowsingContext don't have
+    // any parent BC and shouldn't be considered as top-level.
+    // This is why we check for browserId's.
+    const browsingContext = this.manager.browsingContext;
+    const isTopLevelTarget =
+      !browsingContext.parent &&
+      browsingContext.browserId == sessionData.sessionContext.browserId;
+
+    // Create the actual target actor.
+    const targetActor = new WindowGlobalTargetActor(connection, {
+      docShell: this.docShell,
+      // Targets created from the server side, via Watcher actor and DevToolsFrame JSWindow
+      // actor pair are following WindowGlobal lifecycle. i.e. will be destroyed on any
+      // type of navigation/reload.
+      followWindowGlobalLifeCycle: true,
+      isTopLevelTarget,
+      ignoreSubFrames: isEveryFrameTargetEnabled,
+      sessionContext: sessionData.sessionContext,
+    });
+    targetActor.manage(targetActor);
+    targetActor.createdFromJsWindowActor = true;
+
+    return { connection, targetActor };
+  }
+
+  /**
+   * Supported Queries
+   */
+
+  sendPacket(packet, prefix) {
+    this.sendAsyncMessage("DevToolsFrameChild:packet", { packet, prefix });
+  }
+
+  /**
+   * JsWindowActor API
+   */
+
+  async sendQuery(msg, args) {
+    try {
+      const res = await super.sendQuery(msg, args);
+      return res;
+    } catch (e) {
+      console.error("Failed to sendQuery in DevToolsFrameChild", msg);
+      console.error(e.toString());
+      throw e;
+    }
+  }
+
+  receiveMessage(message) {
+    // Assert that the message is intended for this window global,
+    // except for "packet" messages which use a dedicated routing
+    if (
+      message.name != "DevToolsFrameParent:packet" &&
+      message.data.sessionContext.type == "browser-element"
+    ) {
+      const { browserId } = message.data.sessionContext;
+      // Re-check here, just to ensure that both parent and content processes agree
+      // on what should or should not be watched.
+      if (
+        this.manager.browsingContext.browserId != browserId &&
+        !lazy.isWindowGlobalPartOfContext(
+          this.manager,
+          message.data.sessionContext,
+          {
+            forceAcceptTopLevelTarget: true,
+          }
+        )
+      ) {
+        throw new Error(
+          "Mismatch between DevToolsFrameParent and DevToolsFrameChild " +
+            (this.manager.browsingContext.browserId == browserId
+              ? "window global shouldn't be notified (isWindowGlobalPartOfContext mismatch)"
+              : `expected browsing context with browserId ${browserId}, but got ${this.manager.browsingContext.browserId}`)
+        );
+      }
+    }
+    switch (message.name) {
+      case "DevToolsFrameParent:instantiate-already-available": {
+        const { watcherActorID, connectionPrefix, sessionData } = message.data;
+
+        return this._createTargetActor({
+          watcherActorID,
+          parentConnectionPrefix: connectionPrefix,
+          sessionData,
+          fromInstantiateAlreadyAvailable: true,
+        });
+      }
+      case "DevToolsFrameParent:destroy": {
+        const { watcherActorID, options } = message.data;
+        return this._destroyTargetActor(watcherActorID, options);
+      }
+      case "DevToolsFrameParent:addSessionDataEntry": {
+        const { watcherActorID, sessionContext, type, entries } = message.data;
+        return this._addSessionDataEntry(
+          watcherActorID,
+          sessionContext,
+          type,
+          entries
+        );
+      }
+      case "DevToolsFrameParent:removeSessionDataEntry": {
+        const { watcherActorID, sessionContext, type, entries } = message.data;
+        return this._removeSessionDataEntry(
+          watcherActorID,
+          sessionContext,
+          type,
+          entries
+        );
+      }
+      case "DevToolsFrameParent:packet":
+        return this.emit("packet-received", message);
+      default:
+        throw new Error(
+          "Unsupported message in DevToolsFrameParent: " + message.name
+        );
+    }
+  }
+
+  /**
+   * Return an existing target given a WatcherActor id, a browserId and an optional
+   * browsing context id.
+   * /!\ Note that we may have multiple targets for a given (watcherActorId, browserId) couple,
+   * for example if we have 2 remote iframes sharing the same origin, which is why you
+   * might want to pass a specific browsing context id to filter the list down.
+   *
+   * @param {Object} options
+   * @param {Object} options.watcherActorID
+   * @param {Object} options.sessionContext
+   * @param {Object} options.browsingContextId: Optional browsing context id to narrow the
+   *                 search to a specific browsing context.
+   *
+   * @returns {WindowGlobalTargetActor|null}
+   */
+  _findTargetActor({ watcherActorID, sessionContext, browsingContextId }) {
+    // First let's check if a target was created for this watcher actor in this specific
+    // DevToolsFrameChild instance.
+    const connectionInfo = this._connections.get(watcherActorID);
+    const targetActor = connectionInfo ? connectionInfo.actor : null;
+    if (targetActor) {
+      return targetActor;
+    }
+
+    // If we couldn't find such target, we want to see if a target was created for this
+    // (watcherActorId,browserId, {browsingContextId}) in another DevToolsFrameChild instance.
+    // This might be the case if we're navigating to a new page with server side target
+    // enabled and we want to retrieve the target of the page we're navigating from.
+    if (
+      lazy.isWindowGlobalPartOfContext(this.manager, sessionContext, {
+        forceAcceptTopLevelTarget: true,
+      })
+    ) {
+      // Ensure retrieving the one target actor related to this connection.
+      // This allows to distinguish actors created for various toolboxes.
+      // For ex, regular toolbox versus browser console versus browser toolbox
+      const connectionPrefix = watcherActorID.replace(/watcher\d+$/, "");
+      const targetActors = lazy.TargetActorRegistry.getTargetActors(
+        sessionContext,
+        connectionPrefix
+      );
+
+      if (!browsingContextId) {
+        return targetActors[0] || null;
+      }
+      return targetActors.find(
+        actor => actor.browsingContextID === browsingContextId
+      );
+    }
+    return null;
+  }
+
+  _addSessionDataEntry(watcherActorID, sessionContext, type, entries) {
+    // /!\ We may have an issue here as there could be multiple targets for a given
+    // (watcherActorID,browserId) pair.
+    // This should be clarified as part of Bug 1725623.
+    const targetActor = this._findTargetActor({
+      watcherActorID,
+      sessionContext,
+    });
+
+    if (!targetActor) {
+      throw new Error(
+        `No target actor for this Watcher Actor ID:"${watcherActorID}" / BrowserId:${sessionContext.browserId}`
+      );
+    }
+    return targetActor.addSessionDataEntry(type, entries);
+  }
+
+  _removeSessionDataEntry(watcherActorID, sessionContext, type, entries) {
+    // /!\ We may have an issue here as there could be multiple targets for a given
+    // (watcherActorID,browserId) pair.
+    // This should be clarified as part of Bug 1725623.
+    const targetActor = this._findTargetActor({
+      watcherActorID,
+      sessionContext,
+    });
+    // By the time we are calling this, the target may already have been destroyed.
+    if (targetActor) {
+      return targetActor.removeSessionDataEntry(type, entries);
+    }
+    return null;
+  }
+
+  handleEvent({ type, persisted, target }) {
+    // Ignore any event that may fire for children WindowGlobals/documents
+    if (target != this.document) {
+      return;
+    }
+
+    // DOMWindowCreated is registered from FrameWatcher via `ActorManagerParent.addJSWindowActors`
+    // as a DOM event to be listened to and so is fired by JS Window Actor code platform code.
+    if (type == "DOMWindowCreated") {
+      this.instantiate();
+      return;
+    }
+    // We might have ignored the DOMWindowCreated event because it was the initial about:blank document.
+    // But when loading same-process iframes, we reuse the WindowGlobal of the about:bank document
+    // to load the actual URL loaded in the iframe. This means we won't have a new DOMWindowCreated
+    // for the actual document. There is a DOMDocElementInserted fired just after, that we can catch
+    // to create a target for same-process iframes.
+    // This means that we still do not create any target for the initial documents.
+    // It is complex to instantiate targets for initial documents because:
+    // - it would mean spawning two targets for the same WindowGlobal and sharing the same innerWindowId
+    // - or have WindowGlobalTargets to handle more than one document (it would mean reusing will-navigate/window-ready events
+    // both on client and server)
+    if (type == "DOMDocElementInserted") {
+      this.instantiate({ ignoreIfExisting: true });
+      return;
+    }
+
+    // If persisted=true, this is a BFCache navigation.
+    //
+    // With Fission enabled and bfcacheInParent, BFCache navigations will spawn a new DocShell
+    // in the same process:
+    // * the previous page won't be destroyed, its JSWindowActor will stay alive (`didDestroy` won't be called)
+    //   and a 'pagehide' with persisted=true will be emitted on it.
+    // * the new page page won't emit any DOMWindowCreated, but instead a pageshow with persisted=true
+    //   will be emitted.
+
+    if (type === "pageshow" && persisted) {
+      // Notify all bfcache navigations, even the one for which we don't create a new target
+      // as that's being useful for parent process storage resource watchers.
+      this.sendAsyncMessage("DevToolsFrameChild:bf-cache-navigation-pageshow");
+
+      // Here we are going to re-instantiate a target that got destroyed before while processing a pagehide event.
+      // We force instantiating a new top level target, within `instantiate()` even if server targets are disabled.
+      // But we only do that if bfcacheInParent is enabled. Otherwise for same-process, same-docshell bfcache navigation,
+      // we don't want to spawn new targets.
+      this.instantiate({
+        isBFCache: true,
+      });
+      return;
+    }
+
+    if (type === "pagehide" && persisted) {
+      // Notify all bfcache navigations, even the one for which we don't create a new target
+      // as that's being useful for parent process storage resource watchers.
+      this.sendAsyncMessage("DevToolsFrameChild:bf-cache-navigation-pagehide");
+
+      // We might navigate away for the first top level target,
+      // which isn't using JSWindowActor (it still uses messages manager and is created by the client, via TabDescriptor.getTarget).
+      // We have to unregister it from the TargetActorRegistry, otherwise,
+      // if we navigate back to it, the next DOMWindowCreated won't create a new target for it.
+      const { sharedData } = Services.cpmm;
+      const sessionDataByWatcherActor = sharedData.get(SHARED_DATA_KEY_NAME);
+      if (!sessionDataByWatcherActor) {
+        throw new Error(
+          "Request to instantiate the target(s) for the BrowsingContext, but `sharedData` is empty about watched targets"
+        );
+      }
+
+      const actors = [];
+      // A flag to know if the following for loop ended up destroying all the actors.
+      // It may not be the case if one Watcher isn't having server target switching enabled.
+      let allActorsAreDestroyed = true;
+      for (const [watcherActorID, sessionData] of sessionDataByWatcherActor) {
+        const { sessionContext } = sessionData;
+
+        // /!\ We may have an issue here as there could be multiple targets for a given
+        // (watcherActorID,browserId) pair.
+        // This should be clarified as part of Bug 1725623.
+        const existingTarget = this._findTargetActor({
+          watcherActorID,
+          sessionContext,
+        });
+
+        if (!existingTarget) {
+          continue;
+        }
+
+        // Use `originalWindow` as `window` can be set when a document was selected from
+        // the iframe picker in the toolbox toolbar.
+        if (existingTarget.originalWindow.document != target) {
+          throw new Error("Existing target actor is for a distinct document");
+        }
+        // Do not do anything if both bfcache in parent and server targets are disabled
+        // As history navigations will be handled within the same DocShell and by the
+        // same WindowGlobalTargetActor. The actor will listen to pageshow/pagehide by itself.
+        // We should not destroy any target.
+        if (
+          !this.isBfcacheInParentEnabled &&
+          !sessionContext.isServerTargetSwitchingEnabled
+        ) {
+          allActorsAreDestroyed = false;
+          continue;
+        }
+
+        actors.push({
+          watcherActorID,
+          form: existingTarget.form(),
+        });
+        existingTarget.destroy();
+      }
+
+      if (actors.length) {
+        // The most important is to unregister the actor from TargetActorRegistry,
+        // so that it is no longer present in the list when new DOMWindowCreated fires.
+        // This will also help notify the client that the target has been destroyed.
+        // And if we navigate back to this target, the client will receive the same target actor ID,
+        // so that it is really important to destroy it correctly on both server and client.
+        this.sendAsyncMessage("DevToolsFrameChild:destroy", { actors });
+      }
+
+      if (allActorsAreDestroyed) {
+        // Completely clear this JSWindow Actor.
+        // Do this after having called _findTargetActor,
+        // as it would clear the registered target actors.
+        this.didDestroy();
+      }
+    }
+  }
+
+  didDestroy(options) {
+    logWindowGlobal(this.manager, "Destroy WindowGlobalTarget");
+    for (const [, connectionInfo] of this._connections) {
+      connectionInfo.connection.close(options);
+    }
+    this._connections.clear();
+
+    if (this.loader) {
+      if (this.useCustomLoader) {
+        lazy.releaseDistinctSystemPrincipalLoader(this);
+      }
+      this.loader = null;
+    }
+  }
+}