Add a scoped notifier for pref dictionaries / lists.

chrome/browser/session_startup_pref.cc

Index: chrome/browser/session_startup_pref.cc
diff --git a/chrome/browser/session_startup_pref.cc b/chrome/browser/session_startup_pref.cc
index ff919d05429f17addd9faf17ef56f9f187d29373..1da580269259f6a377adf247fa869e17af36bb96 100644
--- a/chrome/browser/session_startup_pref.cc
+++ b/chrome/browser/session_startup_pref.cc
@@ -10,6 +10,7 @@
 #include "chrome/browser/defaults.h"
 #include "chrome/browser/pref_service.h"
 #include "chrome/browser/profile.h"
+#include "chrome/browser/scoped_pref_update.h"
 #include "chrome/common/pref_names.h"
 
 namespace {
@@ -64,6 +65,7 @@ void SessionStartupPref::SetStartupPref(PrefService* prefs,
   // Always save the URLs, that way the UI can remain consistent even if the
   // user changes the startup type pref.
   // Ownership of the ListValue retains with the pref service.
+  ScopedPrefUpdate update(prefs, prefs::kURLsToRestoreOnStartup);
   ListValue* url_pref_list =
       prefs->GetMutableList(prefs::kURLsToRestoreOnStartup);
   DCHECK(url_pref_list);