Fix homepage migration for users who never changed their settings.

chrome/browser/prefs/session_startup_pref.h

Index: chrome/browser/prefs/session_startup_pref.h
diff --git a/chrome/browser/prefs/session_startup_pref.h b/chrome/browser/prefs/session_startup_pref.h
index 4914e2fc6c58530584b4cc6a18452c0591d95995..e7f67f89d8099c1901cd0752d4845396b53c7d66 100644
--- a/chrome/browser/prefs/session_startup_pref.h
+++ b/chrome/browser/prefs/session_startup_pref.h
@@ -46,6 +46,10 @@ struct SessionStartupPref {
   static SessionStartupPref GetStartupPref(Profile* profile);
   static SessionStartupPref GetStartupPref(PrefService* prefs);
 
+  // Migrates from "Open the home page" to "Open the following URLs", and sets
+  // the list of URLs to a one-item list containing the user's homepage.
+  static void MigrateIfNecessary(PrefService* prefs);
+
   // Whether the startup type and URLs are managed via policy.
   static bool TypeIsManaged(PrefService* prefs);
   static bool URLsAreManaged(PrefService* prefs);