1 files changed, 61 insertions, 0 deletions
diff --git a/devtools/shared/commands/resource/legacy-listeners/root-node.js b/devtools/shared/commands/resource/legacy-listeners/root-node.js
new file mode 100644
index 0000000000..6fa2bcbf22
--- /dev/null
+++ b/devtools/shared/commands/resource/legacy-listeners/root-node.js
@@ -0,0 +1,61 @@
+/* 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 ResourceCommand = require("resource://devtools/shared/commands/resource/resource-command.js");
+
+module.exports = async function ({ targetFront, onAvailable, onDestroyed }) {
+  // XXX: When watching root node for a non top-level target, this will also
+  // ensure the inspector & walker fronts for the target are initialized.
+  // This also implies that we call reparentRemoteFrame on the new walker, which
+  // will create the link between the parent frame NodeFront and the inner
+  // document NodeFront.
+  //
+  // This is not something that will work when the resource is moved to the
+  // server. When it becomes a server side resource, a RootNode would be emitted
+  // directly by the target actor.
+  //
+  // This probably means that the root node resource cannot remain a NodeFront.
+  // It should not be a front and the client should be responsible for
+  // retrieving the corresponding NodeFront.
+  //
+  // The other thing that we are missing with this patch is that we should only
+  // create inspector & walker fronts (and call reparentRemoteFrame) when we get
+  // a RootNode which is directly under an iframe node which is currently
+  // visible and tracked in the markup view.
+  //
+  // For instance, with the following markup:
+  //   html
+  //     body
+  //       div
+  //         iframe
+  //           remote doc
+  //
+  // If the markup view only sees nodes down to `div`, then the client is not
+  // currently tracking the nodeFront for the `iframe`, and getting a new root
+  // node for the remote document should NOT force the iframe to be tracked on
+  // on the client.
+  //
+  // When we get a RootNode resource, we will need a way to check this before
+  // initializing & reparenting the walker.
+  //
+  if (!targetFront.getTrait("isBrowsingContext")) {
+    // The root-node resource is only available on browsing-context targets.
+    return;
+  }
+
+  const inspectorFront = await targetFront.getFront("inspector");
+  inspectorFront.walker.on("root-available", node => {
+    node.resourceType = ResourceCommand.TYPES.ROOT_NODE;
+    return onAvailable([node]);
+  });
+
+  inspectorFront.walker.on("root-destroyed", node => {
+    node.resourceType = ResourceCommand.TYPES.ROOT_NODE;
+    return onDestroyed([node]);
+  });
+
+  await inspectorFront.walker.watchRootNode();
+};