Refactor preference syncing.

chrome/browser/custom_handlers/protocol_handler_registry.cc

Index: chrome/browser/custom_handlers/protocol_handler_registry.cc
diff --git a/chrome/browser/custom_handlers/protocol_handler_registry.cc b/chrome/browser/custom_handlers/protocol_handler_registry.cc
index f2ea2f60fbd506c3e64788455a56e55892f87d11..7edb280dffbe7adeb173daa91be0a878367a8936 100644
--- a/chrome/browser/custom_handlers/protocol_handler_registry.cc
+++ b/chrome/browser/custom_handlers/protocol_handler_registry.cc
@@ -274,9 +274,12 @@ void ProtocolHandlerRegistry::OnIgnoreRegisterProtocolHandler(
 }
 
 void ProtocolHandlerRegistry::RegisterPrefs(PrefService* prefService) {
-  prefService->RegisterListPref(prefs::kRegisteredProtocolHandlers);
-  prefService->RegisterListPref(prefs::kIgnoredProtocolHandlers);
-  prefService->RegisterBooleanPref(prefs::kCustomHandlersEnabled, true);
+  prefService->RegisterListPref(prefs::kRegisteredProtocolHandlers,
+                                PrefService::UNSYNCABLE_PREF);
+  prefService->RegisterListPref(prefs::kIgnoredProtocolHandlers,
+                                PrefService::UNSYNCABLE_PREF);
+  prefService->RegisterBooleanPref(prefs::kCustomHandlersEnabled, true,
+                                   PrefService::UNSYNCABLE_PREF);
 }
 
 void ProtocolHandlerRegistry::SetDefault(const ProtocolHandler& handler) {