bug 1543115: remote: introduce nsIRemoteAgent XPIDL interface; r=remote-protocol-reviewers,maja_zf

Adds an XPIDL interface for the remote agent which we will later use to
initialise and start it from a new command-line handler written in Rust.

Differential Revision: https://phabricator.services.mozilla.com/D50287

--HG--
extra : moz-landing-system : lando

remote/RemoteAgent.jsm

@@ -221,7 +221,10 @@ class RemoteAgentClass {
   // XPCOM
 
   get QueryInterface() {
-    return ChromeUtils.generateQI([Ci.nsICommandLineHandler]);
+    return ChromeUtils.generateQI([
+      Ci.nsICommandLineHandler,
+      Ci.nsIRemoteAgent,
+    ]);
   }
 }
 

remote/moz.build

@@ -9,6 +9,9 @@ DIRS += [
 XPCOM_MANIFESTS += ["components.conf"]
 JAR_MANIFESTS += ["jar.mn"]
 
+XPIDL_MODULE = "remote"
+XPIDL_SOURCES += ["nsIRemoteAgent.idl"]
+
 with Files("**"):
     BUG_COMPONENT = ("Remote Protocol", "Agent")
 with Files("domains/**/Emulation.jsm"):

remote/nsIRemoteAgent.idl

@@ -0,0 +1,44 @@
+/* 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/. */
+
+#include "nsISupports.idl"
+
+/**
+ * The Gecko remote agent is an RPC subsystem that exposes
+ * browser-internal interfaces and services to the surrounding
+ * system.
+ *
+ * Consumers, whether remote or browser-local, can interface with
+ * the browser through an assorted set of services ranging from
+ * document introspection and script evaluation, to instrumentation,
+ * user interaction simulation, and event subscription.
+ */
+[scriptable, uuid(8f685a9d-8181-46d6-a71d-869289099c6d)]
+interface nsIRemoteAgent : nsISupports
+{
+  /**
+   * Whether the remote agent is currently listening for new,
+   * incoming connections.
+   */
+  readonly attribute boolean listening;
+
+  /**
+   * Asynchronously starts the remote agent, and listens for new
+   * connections.
+   *
+   * The address must be a fully qualified URL that uses the "http://"
+   * scheme, and can optionally include a desired port.  If no port
+   * is chosen, the default port 9222 is used.
+   *
+   * If the requested port is 0, the system will atomically allocate
+   * a port.
+   *
+   * A "remote-listening" system observer notification with the URL
+   * of the main target's WebSocket will be emitted once listening.
+   */
+  void listen(in AString aURL);
+
+  /** Stops listening and drops existing connections. */
+  void close();
+};