[Sync] Replace AttachmentIdSet with AttachmentIdList in interfaces.

sync/internal_api/read_transaction.cc

Index: sync/internal_api/read_transaction.cc
diff --git a/sync/internal_api/read_transaction.cc b/sync/internal_api/read_transaction.cc
index 872818fb3b4fb89723afc3aaf78adb0bdd7808b3..9d81b0e4c4d30817148bd223018d470d7356a99b 100644
--- a/sync/internal_api/read_transaction.cc
+++ b/sync/internal_api/read_transaction.cc
@@ -48,10 +48,9 @@ void ReadTransaction::GetDataTypeContext(
 }
 
 void ReadTransaction::GetAttachmentIdsToUpload(ModelType type,
-                                               AttachmentIdSet* id_set) const {
-  DCHECK(id_set);
-  transaction_->directory()->GetAttachmentIdsToUpload(
-      transaction_, type, id_set);
+                                               AttachmentIdList* ids) const {
+  DCHECK(ids);
+  transaction_->directory()->GetAttachmentIdsToUpload(transaction_, type, ids);
 }
 
 std::string ReadTransaction::GetStoreBirthday() const {