Merge again

browser/branding/nightly/pref/firefox-branding.js

@@ -1,4 +1,4 @@
-pref("startup.homepage_override_url","http://www.mozilla.org/projects/%APP%/%VERSION%/whatsnew/");
+pref("startup.homepage_override_url","http://www.mozilla.org/projects/%APP%/%VERSION%/whatsnew/?oldversion=%OLD_VERSION%");
 pref("startup.homepage_welcome_url","http://www.mozilla.org/projects/%APP%/%VERSION%/firstrun/");
 // The time interval between checks for a new version (in seconds)
 pref("app.update.interval", 3600); // 1 hour

browser/branding/official/pref/firefox-branding.js

@@ -1,4 +1,4 @@
-pref("startup.homepage_override_url","http://www.mozilla.com/%LOCALE%/%APP%/%VERSION%/whatsnew/");
+pref("startup.homepage_override_url","http://www.mozilla.com/%LOCALE%/%APP%/%VERSION%/whatsnew/?oldversion=%OLD_VERSION%");
 pref("startup.homepage_welcome_url","http://www.mozilla.com/%LOCALE%/%APP%/%VERSION%/firstrun/");
 // Interval: Time between checks for a new version (in seconds)
 // nightly=6 hours, official=24 hours

browser/components/nsBrowserContentHandler.js

@@ -581,6 +581,15 @@ nsBrowserContentHandler.prototype = {
     var overridePage = "";
     var haveUpdateSession = false;
     try {
+      // Read the old value of homepage_override.mstone before
+      // needHomepageOverride updates it, so that we can later add it to the
+      // URL if we do end up showing an overridePage. This makes it possible
+      // to have the overridePage's content vary depending on the version we're
+      // upgrading from.
+      let old_mstone = "unknown";
+      try {
+        old_mstone = Services.prefs.getCharPref("browser.startup.homepage_override.mstone");
+      } catch (ex) {}
       let override = needHomepageOverride(prefb);
       if (override != OVERRIDE_NONE) {
         // Setup the default search engine to about:home page.
@@ -604,6 +613,8 @@ nsBrowserContentHandler.prototype = {
             overridePage = Services.urlFormatter.formatURLPref("startup.homepage_override_url");
             if (prefb.prefHasUserValue("app.update.postupdate"))
               overridePage = getPostUpdateOverridePage(overridePage);
+
+            overridePage = overridePage.replace("%OLD_VERSION%", old_mstone);
             break;
         }
       }