[Retry][SyncFS] Implement LargestKnownChangeID handling

chrome/browser/sync_file_system/drive_backend/metadata_database_unittest.cc

Index: chrome/browser/sync_file_system/drive_backend/metadata_database_unittest.cc
diff --git a/chrome/browser/sync_file_system/drive_backend/metadata_database_unittest.cc b/chrome/browser/sync_file_system/drive_backend/metadata_database_unittest.cc
index 27da341017e981dd0c37721016d4e9dd6b3e031c..f9724b45928a6ba845691dd54ff6090c0cf0c7f8 100644
--- a/chrome/browser/sync_file_system/drive_backend/metadata_database_unittest.cc
+++ b/chrome/browser/sync_file_system/drive_backend/metadata_database_unittest.cc
@@ -401,6 +401,10 @@ class MetadataDatabaseTest : public testing::Test {
     details->set_change_id(++current_change_id_);
   }
 
+  void ApplyNoopChangeToMetadata(FileMetadata* file) {
+    file->mutable_details()->set_change_id(++current_change_id_);
+  }
+
   void PushToChangeList(scoped_ptr<google_apis::ChangeResource> change,
                         ScopedVector<google_apis::ChangeResource>* changes) {
     changes->push_back(change.release());
@@ -749,6 +753,9 @@ TEST_F(MetadataDatabaseTest, UpdateByChangeListTest) {
                                   &reorganized_file.metadata);
   ApplyContentChangeToMetadata(&updated_file.metadata);
 
+  // Update change ID.
+  ApplyNoopChangeToMetadata(&noop_file.metadata);
+
   ScopedVector<google_apis::ChangeResource> changes;
   PushToChangeList(
       CreateChangeResourceFromMetadata(renamed_file.metadata), &changes);