# HG changeset patch
# User Andreas Tolfsen <ato@sny.no>
# Date 1517079798 0
# Node ID 5f35bfdac21d0fd8dd7fd5885e7e138adfe8dadb
# Parent  bac7864f91ca08e0afcda92891980b9b10498ce7
Bug 1169290 - Reintroduce marionette.enabled pref. r=maja_zf

Some time ago it was decided to remove the marionette.enabled
preference due to concerns that XPCOM addons would be able to
flip arbitrary preferences, potentially causing the remote control
protocol to be activiated unintentionally.

Since then XPCOM based addons have been removed from Firefox in
favour of WebExtensions which do not have the capability to modify
preferences.  There are no current plans to make WebExtensions able
to change preferences:

	https://wiki.mozilla.org/WebExtensions/FAQ#Does_the_WebExtensions_API_provide_access_to_preferences.3F

This patch reintroduces the marionette.enabled preference, which when
flipped to true will enable Marionette and spin up the TCP listener.
Conversely it will stop the TCP listener and disable the component
when switched back to false.

The primary motivation for reintroducing it is the forthcoming
addition of a new navigator.webdriver WebIDL attribute.  The WebIDL
interfaces can be annotated with [Pref="<pref name>"] which will
automatically generate C++ code for determining whether it should be
present in the interface.  This is the easiest and least obstrusive
way for Marionette to cause the webdriver attribute to appear on
the navigator global.

MozReview-Commit-ID: 28wN8Z3Q2a6

diff --git a/testing/marionette/components/marionette.js b/testing/marionette/components/marionette.js
--- a/testing/marionette/components/marionette.js
+++ b/testing/marionette/components/marionette.js
@@ -16,16 +16,17 @@ XPCOMUtils.defineLazyModuleGetter(this, 
 ChromeUtils.defineModuleGetter(this, "Preferences",
     "resource://gre/modules/Preferences.jsm");
 XPCOMUtils.defineLazyGetter(this, "log", () => {
   let log = Log.repository.getLogger("Marionette");
   log.addAppender(new Log.DumpAppender());
   return log;
 });
 
+const PREF_ENABLED = "marionette.enabled";
 const PREF_PORT = "marionette.port";
 const PREF_PORT_FALLBACK = "marionette.defaultPrefs.port";
 const PREF_LOG_LEVEL = "marionette.log.level";
 const PREF_LOG_LEVEL_FALLBACK = "marionette.logging";
 
 const DEFAULT_LOG_LEVEL = "info";
 const NOTIFY_RUNNING = "remote-active";
 
@@ -148,26 +149,44 @@ class MarionetteComponent {
 
     // indicates that all pending window checks have been completed
     // and that we are ready to start the Marionette server
     this.finalUIStartup = false;
 
     log.level = prefs.logLevel;
 
     this.enabled = env.exists(ENV_ENABLED);
+
+    Services.prefs.addObserver(PREF_ENABLED, this);
   }
 
   get running() {
     return this.server && this.server.alive;
   }
 
+  set enabled(value) {
+    Services.prefs.setBoolPref(PREF_ENABLED, value);
+  }
+
+  get enabled() {
+    return Services.prefs.getBoolPref(PREF_ENABLED);
+  }
+
   observe(subject, topic) {
     log.debug(`Received observer notification ${topic}`);
 
     switch (topic) {
+      case "nsPref:changed":
+        if (Services.prefs.getBoolPref(PREF_ENABLED)) {
+          this.init();
+        } else {
+          this.uninit();
+        }
+        break;
+
       case "profile-after-change":
         Services.obs.addObserver(this, "command-line-startup");
         Services.obs.addObserver(this, "sessionstore-windows-restored");
 
         prefs.readFromEnvironment(ENV_PRESERVE_PREFS);
         break;
 
       // In safe mode the command line handlers are getting parsed after the
@@ -284,16 +303,17 @@ class MarionetteComponent {
       Services.obs.notifyObservers(this, NOTIFY_RUNNING);
     }
   }
 
   get QueryInterface() {
     return XPCOMUtils.generateQI([
       Ci.nsICommandLineHandler,
       Ci.nsIMarionette,
+      Ci.nsIObserver,
     ]);
   }
 }
 
 const MarionetteFactory = {
   createInstance(outer, iid) {
     if (outer) {
       throw Cr.NS_ERROR_NO_AGGREGATION;
diff --git a/testing/marionette/prefs/marionette.js b/testing/marionette/prefs/marionette.js
--- a/testing/marionette/prefs/marionette.js
+++ b/testing/marionette/prefs/marionette.js
@@ -1,26 +1,25 @@
 /* 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/. */
 
 /* global pref */
 
 // Marionette is the remote protocol that lets OOP programs communicate
 // with, instrument, and control Gecko.
-//
-// It is included in Firefox, but not enabled by default unless the
-// -marionette flag is passed.
+
+// Controls whether the Marionette component is enabled.
+pref("marionette.enabled", false);
 
 // Delay server startup until a modal dialogue has been clicked to
 // allow time for user to set breakpoints in Browser Toolbox.
 pref("marionette.debugging.clicktostart", false);
 
 // Marionette logging verbosity.  Allowed values are "fatal", "error",
 // "warn", "info", "config", "debug", and "trace".
 pref("marionette.log.level", "info");
 
 // Port to start Marionette server on.
 pref("marionette.port", 2828);
 
-// Sets preferences recommended when using Firefox in automation with
-// Marionette.
+// Sets recommended automation preferences when Marionette is started.
 pref("marionette.prefs.recommended", true);