[Sync] The cryptographer should be able to handle empty or old nigori nodes.

chrome/browser/sync/util/cryptographer_unittest.cc

Index: chrome/browser/sync/util/cryptographer_unittest.cc
diff --git a/chrome/browser/sync/util/cryptographer_unittest.cc b/chrome/browser/sync/util/cryptographer_unittest.cc
index 43a977122bd0700187baebba4c1a945d2ff4897c..9e4f12da6275ccc7ea89e25864287a1621d5a232 100644
--- a/chrome/browser/sync/util/cryptographer_unittest.cc
+++ b/chrome/browser/sync/util/cryptographer_unittest.cc
@@ -230,6 +230,15 @@ TEST(CryptographerTest, NigoriEncryptionTypes) {
   cryptographer2.UpdateEncryptedTypesFromNigori(nigori);
   EXPECT_EQ(encrypted_types, cryptographer.GetEncryptedTypes());
   EXPECT_EQ(encrypted_types, cryptographer2.GetEncryptedTypes());
+
+  // Receiving an empty nigori should not reset any encrypted types.
+  Mock::VerifyAndClearExpectations(&observer);
+  EXPECT_CALL(observer,
+              OnEncryptedTypesChanged(syncable::GetAllRealModelTypes(),
+                                      false));
+  nigori = sync_pb::NigoriSpecifics();
+  cryptographer.UpdateEncryptedTypesFromNigori(nigori);
+  EXPECT_EQ(encrypted_types, cryptographer.GetEncryptedTypes());
 }
 
 TEST(CryptographerTest, EncryptEverythingExplicit) {