ConfigurationPolicyPrefStore refactoring to surface error messages.

chrome/browser/prefs/pref_value_map.cc

Index: chrome/browser/prefs/pref_value_map.cc
diff --git a/chrome/browser/prefs/pref_value_map.cc b/chrome/browser/prefs/pref_value_map.cc
index 3d69cf160dee72610500222f04c591b6d7ee8808..3f1436c372b33c8b8678079192893a33174f9e6f 100644
--- a/chrome/browser/prefs/pref_value_map.cc
+++ b/chrome/browser/prefs/pref_value_map.cc
@@ -141,3 +141,9 @@ void PrefValueMap::GetDifferingKeys(
   for ( ; other_pref != other->prefs_.end(); ++other_pref)
       differing_keys->push_back(other_pref->first);
 }
+
+void PrefValueMap::MergeFrom(const PrefValueMap* other) {
+  Map::const_iterator other_pref(other->prefs_.begin());
+  for ( ; other_pref != other->prefs_.end(); ++other_pref)
+    SetValue(other_pref->first, other_pref->second->DeepCopy());
+}