Add PrefStore::GetValues

components/prefs/pref_value_map.cc

Index: components/prefs/pref_value_map.cc
diff --git a/components/prefs/pref_value_map.cc b/components/prefs/pref_value_map.cc
index f0392d25284319b4a7b62340065d14c4d483f56d..ecacf4c73d4b550f61c292d2047646b6776b0493 100644
--- a/components/prefs/pref_value_map.cc
+++ b/components/prefs/pref_value_map.cc
@@ -157,3 +157,11 @@ void PrefValueMap::GetDifferingKeys(
   for ( ; other_pref != other_prefs.end(); ++other_pref)
       differing_keys->push_back(other_pref->first);
 }
+
+std::unique_ptr<base::DictionaryValue> PrefValueMap::AsDictionaryValue() const {
+  auto dictionary = base::MakeUnique<base::DictionaryValue>();
+  for (const auto& value : prefs_) {
+    dictionary->Set(value.first, value.second->CreateDeepCopy());
+  }
+  return dictionary;
+}