V4LDBM: Get response from GetHashManager, detect severest result

components/safe_browsing_db/v4_database.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 <memory>
 
 #include "base/callback.h"
 #include "base/debug/leak_annotations.h"
 #include "base/files/file_util.h"
 #include "base/memory/ptr_util.h"
@@ skipping 153 matching lines @@
   for (const auto& store_map_iter : *store_map_) {
     (*store_state_map)[store_map_iter.first] = store_map_iter.second->state();
   }
   return store_state_map;
 }
 
 void V4Database::GetStoresMatchingFullHash(
     const FullHash& full_hash,
     const std::unordered_set<UpdateListIdentifier>& stores_to_look,
     StoreAndHashPrefixes* matched_store_and_hash_prefixes) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
   matched_store_and_hash_prefixes->clear();
   for (const UpdateListIdentifier& identifier : stores_to_look) {
     const auto& store_pair = store_map_->find(identifier);
     DCHECK(store_pair != store_map_->end());
     const std::unique_ptr<V4Store>& store = store_pair->second;
     HashPrefix hash_prefix = store->GetMatchingHashPrefix(full_hash);
     if (!hash_prefix.empty()) {
       matched_store_and_hash_prefixes->emplace_back(identifier, hash_prefix);
     }
   }
 }
 
 StoreIdAndFileName::StoreIdAndFileName(const UpdateListIdentifier& list_id,
                                        const std::string& filename)
     : list_id(list_id), filename(filename) {
   DCHECK(!filename.empty());
 }
 
 StoreIdAndFileName::~StoreIdAndFileName() {}
 
 }  // namespace safe_browsing