sync: Implementation of Priority Preferences.

components/user_prefs/pref_registry_syncable.cc

Index: components/user_prefs/pref_registry_syncable.cc
diff --git a/components/user_prefs/pref_registry_syncable.cc b/components/user_prefs/pref_registry_syncable.cc
index 874f8a679d113096639d4723fb599b624efbdde6..81eb65c4366d29ef83effe052efeff3db5e51553 100644
--- a/components/user_prefs/pref_registry_syncable.cc
+++ b/components/user_prefs/pref_registry_syncable.cc
@@ -62,7 +62,7 @@ PrefRegistrySyncable::PrefRegistrySyncable() {
 PrefRegistrySyncable::~PrefRegistrySyncable() {
 }
 
-const std::set<std::string>&
+const PrefRegistrySyncable::PrefToStatus&
 PrefRegistrySyncable::syncable_preferences() const {
   return syncable_preferences_;
 }
@@ -202,11 +202,12 @@ void PrefRegistrySyncable::RegisterSyncablePreference(
     PrefSyncStatus sync_status) {
   PrefRegistry::RegisterPreference(path, default_value);
 
-  if (sync_status == SYNCABLE_PREF) {
-    syncable_preferences_.insert(path);
+  if (sync_status == PrefRegistrySyncable::SYNCABLE_PREF ||
+      sync_status == PrefRegistrySyncable::SYNCABLE_PRIORITY_PREF) {
+    syncable_preferences_[path] = sync_status;
 
     if (!callback_.is_null())
-      callback_.Run(path);
+      callback_.Run(path, sync_status);
   }
 }