[SyncFS] Ensure to pass DB in some utilities

chrome/browser/sync_file_system/drive_backend/drive_backend_util.cc

 // Copyright 2013 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 "chrome/browser/sync_file_system/drive_backend/drive_backend_util.h"
 
 #include "base/logging.h"
 #include "base/memory/scoped_vector.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/threading/thread_restrictions.h"
 #include "chrome/browser/drive/drive_api_util.h"
 #include "chrome/browser/sync_file_system/drive_backend/drive_backend_constants.h"
 #include "chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.h"
 #include "chrome/browser/sync_file_system/drive_backend/metadata_database.pb.h"
 #include "chrome/browser/sync_file_system/logger.h"
 #include "google_apis/drive/drive_api_parser.h"
 #include "google_apis/drive/gdata_wapi_parser.h"
 #include "third_party/leveldatabase/src/include/leveldb/status.h"
 
 namespace sync_file_system {
 namespace drive_backend {
 
 void PutVersionToDB(int64 version, LevelDBWrapper* db) {
-  if (db)
-    db->Put(kDatabaseVersionKey, base::Int64ToString(version));
+  DCHECK(db);
+  db->Put(kDatabaseVersionKey, base::Int64ToString(version));
 }
 
 void PutServiceMetadataToDB(const ServiceMetadata& service_metadata,
                             LevelDBWrapper* db) {
-  if (!db)
-    return;
+  DCHECK(db);
 
   std::string value;
   bool success = service_metadata.SerializeToString(&value);
   DCHECK(success);
   db->Put(kServiceMetadataKey, value);
 }
 
 void PutFileMetadataToDB(const FileMetadata& file, LevelDBWrapper* db) {
-  if (!db)
-    return;
+  DCHECK(db);
 
   std::string value;
   bool success = file.SerializeToString(&value);
   DCHECK(success);
   db->Put(kFileMetadataKeyPrefix + file.file_id(), value);
 }
 
 void PutFileTrackerToDB(const FileTracker& tracker, LevelDBWrapper* db) {
-  if (!db)
-    return;
+  DCHECK(db);
 
   std::string value;
   bool success = tracker.SerializeToString(&value);
   DCHECK(success);
   db->Put(kFileTrackerKeyPrefix + base::Int64ToString(tracker.tracker_id()),
           value);
 }
 
 void PutFileMetadataDeletionToDB(const std::string& file_id,
                                  LevelDBWrapper* db) {
-  if (db)
-    db->Delete(kFileMetadataKeyPrefix + file_id);
+  DCHECK(db);
+  db->Delete(kFileMetadataKeyPrefix + file_id);
 }
 
 void PutFileTrackerDeletionToDB(int64 tracker_id, LevelDBWrapper* db) {
-  if (db)
-    db->Delete(kFileTrackerKeyPrefix + base::Int64ToString(tracker_id));
+  DCHECK(db);
+  db->Delete(kFileTrackerKeyPrefix + base::Int64ToString(tracker_id));
 }
 
 bool HasFileAsParent(const FileDetails& details, const std::string& file_id) {
   for (int i = 0; i < details.parent_folder_ids_size(); ++i) {
     if (details.parent_folder_ids(i) == file_id)
       return true;
   }
   return false;
 }
 
@@ skipping 97 matching lines @@
 
   scoped_ptr<ServiceMetadata> service_metadata(new ServiceMetadata);
   if (!status.ok() || !service_metadata->ParseFromString(value))
     service_metadata->set_next_tracker_id(1);
 
   return service_metadata.Pass();
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system