Deprecate NonThreadSafe in components/sync in favor of SequenceChecker.

components/sync/engine/attachments/on_disk_attachment_store.cc

Index: components/sync/engine/attachments/on_disk_attachment_store.cc
diff --git a/components/sync/engine/attachments/on_disk_attachment_store.cc b/components/sync/engine/attachments/on_disk_attachment_store.cc
index 5ad339d4ff12b892a9c3139ae2c548e333a049ce..e4f083b40386273a2b7b66cee695fd530255c450 100644
--- a/components/sync/engine/attachments/on_disk_attachment_store.cc
+++ b/components/sync/engine/attachments/on_disk_attachment_store.cc
@@ -154,11 +154,13 @@ OnDiskAttachmentStore::OnDiskAttachmentStore(
     const base::FilePath& path)
     : AttachmentStoreBackend(callback_task_runner), path_(path) {}
 
-OnDiskAttachmentStore::~OnDiskAttachmentStore() {}
+OnDiskAttachmentStore::~OnDiskAttachmentStore() {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+}
 
 void OnDiskAttachmentStore::Init(
     const AttachmentStore::InitCallback& callback) {
-  DCHECK(CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   AttachmentStore::Result result_code = OpenOrCreate(path_);
   UMA_HISTOGRAM_ENUMERATION("Sync.Attachments.StoreInitResult", result_code,
                             AttachmentStore::RESULT_SIZE);
@@ -169,7 +171,7 @@ void OnDiskAttachmentStore::Read(
     AttachmentStore::Component component,
     const AttachmentIdList& ids,
     const AttachmentStore::ReadCallback& callback) {
-  DCHECK(CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   std::unique_ptr<AttachmentMap> result_map(new AttachmentMap());
   std::unique_ptr<AttachmentIdList> unavailable_attachments(
       new AttachmentIdList());
@@ -203,7 +205,7 @@ void OnDiskAttachmentStore::Write(
     AttachmentStore::Component component,
     const AttachmentList& attachments,
     const AttachmentStore::WriteCallback& callback) {
-  DCHECK(CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   AttachmentStore::Result result_code =
       AttachmentStore::STORE_INITIALIZATION_FAILED;
 
@@ -221,7 +223,7 @@ void OnDiskAttachmentStore::Write(
 
 void OnDiskAttachmentStore::SetReference(AttachmentStore::Component component,
                                          const AttachmentIdList& ids) {
-  DCHECK(CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   if (!db_)
     return;
   attachment_store_pb::RecordMetadata::Component proto_component =
@@ -239,7 +241,7 @@ void OnDiskAttachmentStore::DropReference(
     AttachmentStore::Component component,
     const AttachmentIdList& ids,
     const AttachmentStore::DropCallback& callback) {
-  DCHECK(CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   AttachmentStore::Result result_code =
       AttachmentStore::STORE_INITIALIZATION_FAILED;
   if (db_) {
@@ -279,7 +281,7 @@ void OnDiskAttachmentStore::ReadMetadataById(
     AttachmentStore::Component component,
     const AttachmentIdList& ids,
     const AttachmentStore::ReadMetadataCallback& callback) {
-  DCHECK(CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   AttachmentStore::Result result_code =
       AttachmentStore::STORE_INITIALIZATION_FAILED;
   std::unique_ptr<AttachmentMetadataList> metadata_list(
@@ -306,7 +308,7 @@ void OnDiskAttachmentStore::ReadMetadataById(
 void OnDiskAttachmentStore::ReadMetadata(
     AttachmentStore::Component component,
     const AttachmentStore::ReadMetadataCallback& callback) {
-  DCHECK(CalledOnValidThread());
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   AttachmentStore::Result result_code =
       AttachmentStore::STORE_INITIALIZATION_FAILED;
   std::unique_ptr<AttachmentMetadataList> metadata_list(