[Sync] Introduce ModelError for USS error handling.

components/reading_list/ios/reading_list_store.cc

 // Copyright 2016 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/reading_list/ios/reading_list_store.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "components/reading_list/ios/proto/reading_list.pb.h"
@@ skipping 102 matching lines @@
   batch_->TransferMetadataChanges(std::move(metadata_change_list));
 }
 
 void ReadingListStore::OnDatabaseLoad(
     syncer::ModelTypeStore::Result result,
     std::unique_ptr<syncer::ModelTypeStore::RecordList> entries) {
   DCHECK(CalledOnValidThread());
   if (result != syncer::ModelTypeStore::Result::SUCCESS) {
     change_processor()->OnMetadataLoaded(
         change_processor()->CreateAndUploadError(
-            FROM_HERE, "Cannot load Reading List Database."),
+            FROM_HERE, "Cannot load Reading List Database.", type()),
         nullptr);
     return;
   }
   auto loaded_entries =
       base::MakeUnique<ReadingListStoreDelegate::ReadingListEntries>();
 
   for (const syncer::ModelTypeStore::Record& r : *entries.get()) {
     reading_list::ReadingListLocal proto;
     if (!proto.ParseFromString(r.value)) {
       continue;
@@ skipping 308 matching lines @@
     if (rhs.first_read_time_us() == 0 && lhs.first_read_time_us() != 0) {
       return false;
     }
     if (rhs.first_read_time_us() > lhs.first_read_time_us() &&
         lhs.first_read_time_us() != 0) {
       return false;
     }
   }
   return true;
 }