--- a/toolkit/mozapps/extensions/test/browser/browser_bug562797.js
+++ b/toolkit/mozapps/extensions/test/browser/browser_bug562797.js
@@ -1,17 +1,16 @@
 /* Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
 /**
  * Tests that history navigation works for the add-ons manager.
  */
 
-const PREF_DISCOVERURL = "extensions.webservice.discoverURL";
 const MAIN_URL = "https://example.com/" + RELATIVE_DIR + "discovery.html";
 const SECOND_URL = "https://example.com/" + RELATIVE_DIR + "releaseNotes.xhtml";
 
 var gLoadCompleteCallback = null;
 
 var gProgressListener = {
   onStateChange: function(aWebProgress, aRequest, aStateFlags, aStatus) {
     // Only care about the network stop status events
@@ -53,19 +52,16 @@ function clickLink(aManager, aId, aCallb
 }
 
 function test() {
   requestLongerTimeout(2);
 
   waitForExplicitFinish();
 
   Services.prefs.setCharPref(PREF_DISCOVERURL, MAIN_URL);
-  registerCleanupFunction(function() {
-    Services.prefs.clearUserPref(PREF_DISCOVERURL);
-  });
 
   var gProvider = new MockProvider();
   gProvider.createAddons([{
     id: "test1@tests.mozilla.org",
     name: "Test add-on 1",
     description: "foo"
   },
   {

--- a/toolkit/mozapps/extensions/test/browser/browser_discovery.js
+++ b/toolkit/mozapps/extensions/test/browser/browser_discovery.js
@@ -1,16 +1,15 @@
 /* Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
 // Tests that the discovery view loads properly
 
 const PREF_GETADDONS_CACHE_ENABLED = "extensions.getAddons.cache.enabled";
-const PREF_DISCOVERURL = "extensions.webservice.discoverURL";
 const MAIN_URL = "https://example.com/" + RELATIVE_DIR + "discovery.html";
 
 var gManagerWindow;
 var gCategoryUtilities;
 var gProvider;
 
 var gLoadCompleteCallback = null;
 
@@ -31,25 +30,22 @@ var gProgressListener = {
   onProgressChange: function() { },
   onStatusChange: function() { },
 
   QueryInterface: XPCOMUtils.generateQI([Ci.nsIWebProgressListener,
                                          Ci.nsISupportsWeakReference]),
 };
 
 function test() {
-  var currentURL = Services.prefs.getCharPref(PREF_DISCOVERURL);
-
   // Switch to a known url
   Services.prefs.setCharPref(PREF_DISCOVERURL, MAIN_URL);
   // Temporarily enable caching
   Services.prefs.setBoolPref(PREF_GETADDONS_CACHE_ENABLED, true);
 
   registerCleanupFunction(function() {
-    Services.prefs.setCharPref(PREF_DISCOVERURL, currentURL);
     Services.prefs.setBoolPref(PREF_GETADDONS_CACHE_ENABLED, false);
   });
 
   waitForExplicitFinish();
 
   gProvider = new MockProvider();
 
   gProvider.createAddons([{

--- a/toolkit/mozapps/extensions/test/browser/head.js
+++ b/toolkit/mozapps/extensions/test/browser/head.js
@@ -16,40 +16,45 @@ var gTestInWindow = /-window$/.test(path
 pathParts.splice(pathParts.length - 1);
 pathParts.push("browser");
 
 const RELATIVE_DIR = pathParts.slice(4).join("/") + "/";
 
 const TESTROOT = "http://example.com/" + RELATIVE_DIR;
 const TESTROOT2 = "http://example.org/" + RELATIVE_DIR;
 const CHROMEROOT = pathParts.join("/") + "/";
+const PREF_DISCOVERURL = "extensions.webservice.discoverURL";
 
 const MANAGER_URI = "about:addons";
 const INSTALL_URI = "chrome://mozapps/content/xpinstall/xpinstallConfirm.xul";
 const PREF_LOGGING_ENABLED = "extensions.logging.enabled";
 const PREF_SEARCH_MAXRESULTS = "extensions.getAddons.maxResults";
 
 var gPendingTests = [];
 var gTestsRun = 0;
 var gTestStart = null;
 
 var gUseInContentUI = !gTestInWindow && ("switchToTabHavingURI" in window);
 
+var gDiscoveryURL = Services.prefs.getCharPref(PREF_DISCOVERURL);
+
 // Turn logging on for all tests
 Services.prefs.setBoolPref(PREF_LOGGING_ENABLED, true);
 // Turn off remote results in searches
 Services.prefs.setIntPref(PREF_SEARCH_MAXRESULTS, 0);
 registerCleanupFunction(function() {
   Services.prefs.clearUserPref(PREF_LOGGING_ENABLED);
   try {
     Services.prefs.clearUserPref(PREF_SEARCH_MAXRESULTS);
   }
   catch (e) {
   }
 
+  Services.prefs.setCharPref(PREF_DISCOVERURL, gDiscoveryURL);
+
   // Throw an error if the add-ons manager window is open anywhere
   var windows = Services.wm.getEnumerator("Addons:Manager");
   if (windows.hasMoreElements())
     ok(false, "Found unexpected add-ons manager window still open");
   while (windows.hasMoreElements())
     windows.getNext().QueryInterface(Ci.nsIDOMWindow).close();
 
   windows = Services.wm.getEnumerator("Addons:Compatibility");