Assert run on correct Sequence instead of Thread in LoopbackServer.

This is ground work for having ProfileSyncService's backend task runner use the
ThreadPool.

This class in particular affects LocalSynctTest.Shouldstart when work is done
fully on the Threadpool.

Bug: 1014464
Change-Id: Id91c6b1682648a6fdb38efef5145ab4d6af0b2e6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1865427
Commit-Queue: Oliver Li <olivierli@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#707363}

components/sync/engine_impl/loopback_server/loopback_server.cc

@@ -15,6 +15,7 @@
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/rand_util.h"
+#include "base/sequence_checker.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
@@ -255,7 +256,7 @@ std::string LoopbackServer::GenerateNewKeystoreKey() const {
 bool LoopbackServer::CreatePermanentBookmarkFolder(
     const std::string& server_tag,
     const std::string& name) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   std::unique_ptr<LoopbackServerEntity> entity =
       PersistentPermanentEntity::CreateNew(
           syncer::BOOKMARKS, server_tag, name,
@@ -306,7 +307,7 @@ void LoopbackServer::SaveEntity(std::unique_ptr<LoopbackServerEntity> entity) {
 
 net::HttpStatusCode LoopbackServer::HandleCommand(const string& request,
                                                   std::string* response) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   response->clear();
 
   sync_pb::ClientToServerMessage message;
@@ -663,7 +664,7 @@ bool LoopbackServer::HandleCommitRequest(
 }
 
 void LoopbackServer::ClearServerData() {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   entities_.clear();
   keystore_keys_.clear();
   ++store_birthday_;
@@ -672,13 +673,13 @@ void LoopbackServer::ClearServerData() {
 }
 
 std::string LoopbackServer::GetStoreBirthday() const {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   return base::NumberToString(store_birthday_);
 }
 
 std::vector<sync_pb::SyncEntity> LoopbackServer::GetSyncEntitiesByModelType(
     ModelType model_type) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   std::vector<sync_pb::SyncEntity> sync_entities;
   for (const auto& kv : entities_) {
     const LoopbackServerEntity& entity = *kv.second;
@@ -694,7 +695,7 @@ std::vector<sync_pb::SyncEntity> LoopbackServer::GetSyncEntitiesByModelType(
 
 std::vector<sync_pb::SyncEntity>
 LoopbackServer::GetPermanentSyncEntitiesByModelType(ModelType model_type) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   std::vector<sync_pb::SyncEntity> sync_entities;
   for (const auto& kv : entities_) {
     const LoopbackServerEntity& entity = *kv.second;
@@ -710,7 +711,7 @@ LoopbackServer::GetPermanentSyncEntitiesByModelType(ModelType model_type) {
 
 std::unique_ptr<base::DictionaryValue>
 LoopbackServer::GetEntitiesAsDictionaryValue() {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   std::unique_ptr<base::DictionaryValue> dictionary(
       new base::DictionaryValue());
 
@@ -783,7 +784,7 @@ bool LoopbackServer::ModifyBookmarkEntity(
 }
 
 void LoopbackServer::SerializeState(sync_pb::LoopbackServerProto* proto) const {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
 
   proto->set_version(kCurrentLoopbackServerProtoVersion);
   proto->set_store_birthday(store_birthday_);
@@ -798,7 +799,7 @@ void LoopbackServer::SerializeState(sync_pb::LoopbackServerProto* proto) const {
 
 bool LoopbackServer::DeSerializeState(
     const sync_pb::LoopbackServerProto& proto) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   DCHECK_EQ(proto.version(), kCurrentLoopbackServerProtoVersion);
 
   store_birthday_ = proto.store_birthday();

components/sync/engine_impl/loopback_server/loopback_server.h

@@ -15,7 +15,7 @@
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "base/optional.h"
-#include "base/threading/thread_checker.h"
+#include "base/sequence_checker.h"
 #include "base/values.h"
 #include "components/sync/base/model_type.h"
 #include "components/sync/engine_impl/loopback_server/loopback_server_entity.h"
@@ -235,8 +235,8 @@ class LoopbackServer {
   // The file used to store the local sync data.
   base::FilePath persistent_file_;
 
-  // Used to verify that LoopbackServer is only used from one thread.
-  base::ThreadChecker thread_checker_;
+  // Used to verify that LoopbackServer is only used from one sequence.
+  SEQUENCE_CHECKER(sequence_checker_);
 
   // Used to observe the completion of commit messages for the sake of testing.
   ObserverForTests* observer_for_tests_;