Bug 1077740 - Handle multiple homepages when resetting to about:home. r=gavin

browser/components/nsBrowserGlue.js

@@ -1623,11 +1623,25 @@ BrowserGlue.prototype = {
       // Reset homepage pref for users who have it set to start.mozilla.org
       // or google.com/firefox.
       const HOMEPAGE_PREF = "browser.startup.homepage";
-      let uri = Services.prefs.getComplexValue(HOMEPAGE_PREF,
-                                               Ci.nsIPrefLocalizedString).data;
-      if (uri && (uri.startsWith("http://start.mozilla.org") ||
-                  /^https?:\/\/(www\.)?google\.[a-z.]+\/firefox/i.test(uri))) {
-        Services.prefs.clearUserPref(HOMEPAGE_PREF);
+      if (Services.prefs.prefHasUserValue(HOMEPAGE_PREF)) {
+        const DEFAULT =
+          Services.prefs.getDefaultBranch(HOMEPAGE_PREF)
+                        .getComplexValue("", Ci.nsIPrefLocalizedString).data;
+        let value =
+          Services.prefs.getComplexValue(HOMEPAGE_PREF, Ci.nsISupportsString);
+        let updated =
+          value.data.replace(/https?:\/\/start\.mozilla\.org[^|]*/i, DEFAULT)
+                    .replace(/https?:\/\/(www\.)?google\.[a-z.]+\/firefox[^|]*/i,
+                             DEFAULT);
+        if (updated != value.data) {
+          if (updated == DEFAULT) {
+            Services.prefs.clearUserPref(HOMEPAGE_PREF);
+          } else {
+            value.data = updated;
+            Services.prefs.setComplexValue(HOMEPAGE_PREF,
+                                           Ci.nsISupportsString, value);
+          }
+        }
       }
     }