[Sync] Wrap model type specifics in oneof.

components/sync/protocol/proto_value_conversions_unittest.cc

Index: components/sync/protocol/proto_value_conversions_unittest.cc
diff --git a/components/sync/protocol/proto_value_conversions_unittest.cc b/components/sync/protocol/proto_value_conversions_unittest.cc
index 9015e5c344053250e2705ac6aa51952b4fae47db..65daee6446ff82dd18828c31127deb9a23a0989c 100644
--- a/components/sync/protocol/proto_value_conversions_unittest.cc
+++ b/components/sync/protocol/proto_value_conversions_unittest.cc
@@ -351,8 +351,8 @@ TEST_F(ProtoValueConversionsTest, WifiCredentialSpecificsToValue) {
 }
 
 // TODO(akalin): Figure out how to better test EntitySpecificsToValue.
-
-TEST_F(ProtoValueConversionsTest, EntitySpecificsToValue) {
+// TODO(skym): Rework this case. It is no longer valid to set multiple fields.

[bartekg, 2017/01/24 19:19:39]

Maybe there is a way to turn this into a parameterized test? Using lite proto
runtime makes it tricky.

One way would be to use a field id as a parameter, generate serialized protos,
parse them and discard unrecognized fields.

+/*TEST_F(ProtoValueConversionsTest, EntitySpecificsToValue) {
   sync_pb::EntitySpecifics specifics;
 // Touch the extensions to make sure it shows up in the generated
 // value.
@@ -402,7 +402,7 @@ TEST_F(ProtoValueConversionsTest, EntitySpecificsToValue) {
   EXPECT_EQ(MODEL_TYPE_COUNT - FIRST_REAL_MODEL_TYPE -
                 (LAST_PROXY_TYPE - FIRST_PROXY_TYPE + 1),
             static_cast<int>(value->size()));
-}
+}*/
 
 TEST_F(ProtoValueConversionsTest, UniquePositionToValue) {
   sync_pb::SyncEntity entity;