Bug 1285373 P3 Test that sdk/event/chrome observer channels can be GC'd. r=gabor

addon-sdk/source/test/leak/jetpack-package.ini

@@ -4,3 +4,4 @@ support-files =
 
 [test-leak-window-events.js]
 [test-leak-event-dom-closed-window.js]
+[test-leak-event-chrome.js]

addon-sdk/source/test/leak/leak-utils.js

@@ -31,6 +31,7 @@ function gc() {
     Cu.schedulePreciseGC(genGCCallback());
   });
 }
+exports.gc = gc;
 
 // Execute the given test function and verify that we did not leak windows
 // in the process.  The test function must return a promise or be a generator.

addon-sdk/source/test/leak/test-leak-event-chrome.js

@@ -0,0 +1,41 @@
+/* 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 { gc } = require("./leak-utils");
+const { Loader } = require("sdk/test/loader");
+const { Cu } = require("chrome");
+const { Services } = Cu.import("resource://gre/modules/Services.jsm", {});
+
+exports["test sdk/event/chrome does not leak when not referenced"] = function*(assert) {
+  let loader = Loader(module);
+  let { observe } = loader.require("sdk/event/chrome");
+  let { on } = loader.require("sdk/event/core");
+
+  let gotFooEvent = false;
+  on(observe("test-foo"), "data", function(evt) {
+    gotFooEvent = true;
+  });
+
+  let bar = observe("test-bar");
+  let barPromise = new Promise(resolve => {
+    on(bar, "data", function(evt) {
+      assert.ok(!gotFooEvent, "should not have gotten test-foo event");
+      resolve();
+    });
+  });
+
+  // This should clear the test-foo observer channel because we are not
+  // holding a reference to it above.
+  yield gc();
+
+  Services.obs.notifyObservers(null, "test-foo", null);
+  Services.obs.notifyObservers(null, "test-bar", null);
+
+  yield barPromise;
+
+  loader.unload();
+}
+
+require("sdk/test").run(exports);