Refactor preference syncing.

chrome/browser/extensions/extension_updater.cc

Index: chrome/browser/extensions/extension_updater.cc
diff --git a/chrome/browser/extensions/extension_updater.cc b/chrome/browser/extensions/extension_updater.cc
index ff17effcc66251161acac5dfc47bc37d6dca1d0d..5ce777a4586271218779b7dc5ea2daee98558394 100644
--- a/chrome/browser/extensions/extension_updater.cc
+++ b/chrome/browser/extensions/extension_updater.cc
@@ -499,12 +499,14 @@ ExtensionUpdater::~ExtensionUpdater() {
 static void EnsureInt64PrefRegistered(PrefService* prefs,
                                       const char name[]) {
   if (!prefs->FindPreference(name))
-    prefs->RegisterInt64Pref(name, 0);
+    prefs->RegisterInt64Pref(name, 0, false /* don't sync pref */);
 }
 
 static void EnsureBlacklistVersionPrefRegistered(PrefService* prefs) {
   if (!prefs->FindPreference(kExtensionBlacklistUpdateVersion))
-    prefs->RegisterStringPref(kExtensionBlacklistUpdateVersion, "0");
+    prefs->RegisterStringPref(kExtensionBlacklistUpdateVersion,
+                              "0",
+                              false /* don't sync pref */);
 }
 
 // The overall goal here is to balance keeping clients up to date while