[Sync] Support commit only types.

components/sync/user_events/user_event_sync_bridge_unittest.cc

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/sync/user_events/user_event_sync_bridge.h"
 
 #include <map>
 #include <set>
 
 #include "base/bind.h"
@@ skipping 110 matching lines @@
 
   EXPECT_EQ(4u, processor().put_multimap().size());
   std::set<std::string> unique_storage_keys;
   for (const auto& kv : processor().put_multimap()) {
     unique_storage_keys.insert(kv.first);
   }
   EXPECT_EQ(2u, unique_storage_keys.size());
   bridge()->GetAllData(base::Bind(&VerifyDataBatchCount, 4));
 }
 
+TEST_F(UserEventSyncBridgeTest, ApplySyncChanges) {
+  bridge()->RecordUserEvent(SpecificsUniquePtr(1u, 1u, 1u));
+  bridge()->RecordUserEvent(SpecificsUniquePtr(2u, 2u, 2u));
+  bridge()->GetAllData(base::Bind(&VerifyDataBatchCount, 2));
+
+  const std::string storage_key = processor().put_multimap().begin()->first;
+  auto error_on_delete =
+      bridge()->ApplySyncChanges(bridge()->CreateMetadataChangeList(),
+                                 {EntityChange::CreateDelete(storage_key)});
+  EXPECT_FALSE(error_on_delete);
+  bridge()->GetAllData(base::Bind(&VerifyDataBatchCount, 1));
+}
+
 }  // namespace
 
 }  // namespace syncer