Bug 1276271 P2 Verify responsive design UI does not leak when window is closed. r=jryans

devtools/client/responsivedesign/test/browser.ini

@@ -17,3 +17,4 @@ skip-if = e10s && debug # Bug 1252201 - Docshell leak on debug e10s
 [browser_responsiveuiaddcustompreset.js]
 [browser_responsive_devicewidth.js]
 [browser_responsiveui_customuseragent.js]
+[browser_responsiveui_window_close.js]

devtools/client/responsivedesign/test/browser_responsiveui_window_close.js

@@ -0,0 +1,25 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(function* () {
+  let newWindowPromise = BrowserTestUtils.waitForNewWindow();
+  window.open("about:blank", "_blank");
+  let newWindow = yield newWindowPromise;
+
+  newWindow.focus();
+  yield once(newWindow.gBrowser, "load", true);
+
+  let tab = newWindow.gBrowser.selectedTab;
+  yield ResponsiveUIManager.runIfNeeded(newWindow, tab);
+
+  // Close the window on a tab with an active responsive design UI and
+  // wait for the UI to gracefully shutdown.  This has leaked the window
+  // in the past.
+  ok(ResponsiveUIManager.isActiveForTab(tab),
+     "ResponsiveUI should be active for tab when the window is closed");
+  let offPromise = once(ResponsiveUIManager, "off");
+  yield BrowserTestUtils.closeWindow(newWindow);
+  yield offPromise;
+});