[Sync] Added integ tests to verify UserEvents retry on TRANSIENT_ERROR.

components/sync/test/fake_server/fake_server.cc

 // Copyright 2014 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/test/fake_server/fake_server.h"
 
 #include <algorithm>
 #include <limits>
 #include <set>
 #include <utility>
@@ skipping 383 matching lines @@
   } else {
     entity = UniqueClientEntity::Create(client_entity);
   }
 
   const std::string id = entity->id();
   SaveEntity(std::move(entity));
   BuildEntryResponseForSuccessfulCommit(id, entry_response);
   return id;
 }
 
+void FakeServer::OverrideResponseType(
+    ResponseTypeProvider response_type_override) {
+  response_type_override_ = std::move(response_type_override);
+}
+
 void FakeServer::BuildEntryResponseForSuccessfulCommit(
     const std::string& entity_id,
     sync_pb::CommitResponse_EntryResponse* entry_response) {
   EntityMap::const_iterator iter = entities_.find(entity_id);
   CHECK(iter != entities_.end());
   const FakeServerEntity& entity = *iter->second;
-  entry_response->set_response_type(sync_pb::CommitResponse::SUCCESS);
+  entry_response->set_response_type(response_type_override_
+                                        ? response_type_override_.Run(entity)
+                                        : sync_pb::CommitResponse::SUCCESS);
   entry_response->set_id_string(entity.id());
 
   if (entity.IsDeleted()) {
     entry_response->set_version(entity.GetVersion() + 1);
   } else {
     entry_response->set_version(entity.GetVersion());
     entry_response->set_name(entity.GetName());
   }
 }
 
@@ skipping 275 matching lines @@
   DCHECK(thread_checker_.CalledOnValidThread());
   return weak_ptr_factory_.GetWeakPtr();
 }
 
 std::string FakeServer::GetStoreBirthday() const {
   DCHECK(thread_checker_.CalledOnValidThread());
   return base::Int64ToString(store_birthday_);
 }
 
 }  // namespace fake_server