1 files changed, 202 insertions, 0 deletions
diff --git a/devtools/client/fronts/watcher.js b/devtools/client/fronts/watcher.js
new file mode 100644
index 0000000000..1a7499561a
--- /dev/null
+++ b/devtools/client/fronts/watcher.js
@@ -0,0 +1,202 @@
+/* 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 { watcherSpec } = require("resource://devtools/shared/specs/watcher.js");
+const {
+  FrontClassWithSpec,
+  registerFront,
+} = require("resource://devtools/shared/protocol.js");
+
+loader.lazyRequireGetter(
+  this,
+  "WindowGlobalTargetFront",
+  "resource://devtools/client/fronts/targets/window-global.js",
+  true
+);
+loader.lazyRequireGetter(
+  this,
+  "ContentProcessTargetFront",
+  "resource://devtools/client/fronts/targets/content-process.js",
+  true
+);
+loader.lazyRequireGetter(
+  this,
+  "WorkerTargetFront",
+  "resource://devtools/client/fronts/targets/worker.js",
+  true
+);
+
+class WatcherFront extends FrontClassWithSpec(watcherSpec) {
+  constructor(client, targetFront, parentFront) {
+    super(client, targetFront, parentFront);
+
+    this._onTargetAvailable = this._onTargetAvailable.bind(this);
+    this._onTargetDestroyed = this._onTargetDestroyed.bind(this);
+
+    // Convert form, which is just JSON object to Fronts for these two events
+    this.on("target-available-form", this._onTargetAvailable);
+    this.on("target-destroyed-form", this._onTargetDestroyed);
+  }
+
+  form(json) {
+    this.actorID = json.actor;
+    this.traits = json.traits;
+  }
+
+  _onTargetAvailable(form) {
+    let front;
+    if (form.actor.includes("/contentProcessTarget")) {
+      front = new ContentProcessTargetFront(this.conn, null, this);
+    } else if (form.actor.includes("/workerTarget")) {
+      front = new WorkerTargetFront(this.conn, null, this);
+    } else {
+      front = new WindowGlobalTargetFront(this.conn, null, this);
+    }
+    front.actorID = form.actor;
+    front.form(form);
+    this.manage(front);
+    this.emit("target-available", front);
+  }
+
+  _onTargetDestroyed(form, options = {}) {
+    const front = this._getTargetFront(form);
+
+    // When server side target switching is off,
+    // the watcher may notify us about the top level target destruction a bit late.
+    // The descriptor (`this.parentFront`) already switched to the new target.
+    // Missing `target-destroyed` isn't critical when target switching is off
+    // as `TargetCommand.switchToTarget` will end calling `TargetCommandonTargetDestroyed` for all
+    // existing targets.
+    // https://searchfox.org/mozilla-central/rev/af8e5d37fd56be90ccddae2203e7b875d3f3ae87/devtools/shared/commands/target/target-command.js#166-173
+    if (front) {
+      this.emit("target-destroyed", front, options);
+    }
+  }
+
+  _getTargetFront(form) {
+    let front = this.getActorByID(form.actor);
+    // For top level target, the target will be a child of the descriptor front,
+    // which happens to be the parent front of the watcher.
+    if (!front) {
+      front = this.parentFront.getActorByID(form.actor);
+    }
+    return front;
+  }
+
+  /**
+   * Retrieve the already existing WindowGlobalTargetFront for the parent
+   * BrowsingContext of the given BrowsingContext ID.
+   */
+  async getParentWindowGlobalTarget(browsingContextID) {
+    const id = await this.getParentBrowsingContextID(browsingContextID);
+    if (!id) {
+      return null;
+    }
+    return this.getWindowGlobalTarget(id);
+  }
+
+  /**
+   * Memoized getter for the "blackboxing" actor
+   */
+  async getBlackboxingActor() {
+    if (!this._blackboxingActor) {
+      this._blackboxingActor = await super.getBlackboxingActor();
+    }
+    return this._blackboxingActor;
+  }
+  /**
+   * Memoized getter for the "breakpoint-list" actor
+   */
+  async getBreakpointListActor() {
+    if (!this._breakpointListActor) {
+      this._breakpointListActor = await super.getBreakpointListActor();
+    }
+    return this._breakpointListActor;
+  }
+
+  /**
+   * Memoized getter for the "target-configuration" actor
+   */
+  async getTargetConfigurationActor() {
+    if (!this._targetConfigurationActor) {
+      this._targetConfigurationActor =
+        await super.getTargetConfigurationActor();
+    }
+    return this._targetConfigurationActor;
+  }
+
+  /**
+   * Memoized getter for the "thread-configuration" actor
+   */
+  async getThreadConfigurationActor() {
+    if (!this._threadConfigurationActor) {
+      this._threadConfigurationActor =
+        await super.getThreadConfigurationActor();
+    }
+    return this._threadConfigurationActor;
+  }
+
+  /**
+   * For a given BrowsingContext ID, return the already existing WindowGlobalTargetFront
+   */
+  async getWindowGlobalTarget(id) {
+    // First scan the watcher children as the watcher manages all the targets
+    for (const front of this.poolChildren()) {
+      if (front.browsingContextID == id) {
+        return front;
+      }
+    }
+    // But the top level target will be created by the Descriptor.getTarget() method
+    // and so be hosted in the Descriptor's pool.
+    // The parent front of the WatcherActor happens to be the Descriptor Actor.
+    // This code could go away or be simplified if the Descriptor starts fetch all
+    // the targets, including the top level one via the Watcher. i.e. drop Descriptor.getTarget().
+    const topLevelTarget = await this.parentFront.getTarget();
+    if (topLevelTarget?.browsingContextID == id) {
+      return topLevelTarget;
+    }
+
+    // If we could not find a window global target for the provided id, the
+    // window global might not be the topmost one of a given process (isProcessRoot == true).
+    // For now we only create targets for the top window global of each process,
+    // so we recursively check the parent browsing context ids
+    // until we find a valid target.
+    const parentBrowsingContextID = await this.getParentBrowsingContextID(id);
+    if (parentBrowsingContextID && parentBrowsingContextID !== id) {
+      return this.getWindowGlobalTarget(parentBrowsingContextID);
+    }
+
+    return null;
+  }
+
+  getWindowGlobalTargetByInnerWindowId(innerWindowId) {
+    for (const front of this.poolChildren()) {
+      if (front.innerWindowId == innerWindowId) {
+        return front;
+      }
+    }
+    // Use getCachedTarget in order to have a fully synchronous method
+    // as the callsite in ResourceCommand benefit from being synchronous.
+    // Here we care only about already existing resource and do not need to
+    // wait for the next target to come.
+    const topLevelTarget = this.parentFront.getCachedTarget();
+    if (topLevelTarget?.innerWindowId == innerWindowId) {
+      return topLevelTarget;
+    }
+    console.error("Unable to find target with innerWindowId:" + innerWindowId);
+    return null;
+  }
+
+  /**
+   * Memoized getter for the "networkParent" actor
+   */
+  async getNetworkParentActor() {
+    if (!this._networkParentActor) {
+      this._networkParentActor = await super.getNetworkParentActor();
+    }
+    return this._networkParentActor;
+  }
+}
+registerFront(WatcherFront);