Add PrefStore::GetValues

components/prefs/json_pref_store.cc

Index: components/prefs/json_pref_store.cc
diff --git a/components/prefs/json_pref_store.cc b/components/prefs/json_pref_store.cc
index 026606a7b762fb3cbac735ec1e5bd068a12bf205..a9a39227d3fef97904abee35390c2fc54dc30ceb 100644
--- a/components/prefs/json_pref_store.cc
+++ b/components/prefs/json_pref_store.cc
@@ -190,6 +190,10 @@ bool JsonPrefStore::GetValue(const std::string& key,
   return true;
 }
 
+std::unique_ptr<base::DictionaryValue> JsonPrefStore::GetValues() const {
+  return prefs_->CreateDeepCopy();
+}
+
 void JsonPrefStore::AddObserver(PrefStore::Observer* observer) {
   DCHECK(CalledOnValidThread());