[SyncFS] [Refactoring] Change RemovePrefix() to return bool

chrome/browser/sync_file_system/drive_backend/metadata_db_migration_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/metadata_db_migration_util.h"
 
 #include "base/files/file_path.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string_util.h"
 #include "chrome/browser/sync_file_system/drive_backend/drive_backend_util.h"
@@ skipping 64 matching lines @@
     case DriveMetadata_ResourceType_RESOURCE_TYPE_FILE:
       return AddWapiFilePrefix(resource_id);
     case DriveMetadata_ResourceType_RESOURCE_TYPE_FOLDER:
       return AddWapiFolderPrefix(resource_id);
   }
   NOTREACHED();
   return resource_id;
 }
 
 std::string RemoveWapiIdPrefix(const std::string& resource_id) {
-  if (StartsWithASCII(resource_id, kWapiFileIdPrefix, true))
-    return RemovePrefix(resource_id, kWapiFileIdPrefix);
-  if (StartsWithASCII(resource_id, kWapiFolderIdPrefix, true))
-    return RemovePrefix(resource_id, kWapiFolderIdPrefix);
+  std::string value;
+  if (RemovePrefix(resource_id, kWapiFileIdPrefix, &value))
+    return value;
+  if (RemovePrefix(resource_id, kWapiFolderIdPrefix, &value))
+    return value;
   return resource_id;
 }
 
 SyncStatusCode MigrateDatabaseFromV0ToV1(leveldb::DB* db) {
   // Version 0 database format:
   //   key: "CHANGE_STAMP"
   //   value: <Largest Changestamp>
   //
   //   key: "SYNC_ROOT_DIR"
   //   value: <Resource ID of the sync root directory>
@@ skipping 35 matching lines @@
   const char kMetadataKeySeparator = ' ';
 
   leveldb::WriteBatch write_batch;
   write_batch.Put(kDatabaseVersionKey, "1");
 
   scoped_ptr<leveldb::Iterator> itr(db->NewIterator(leveldb::ReadOptions()));
   for (itr->Seek(kDriveMetadataKeyPrefix); itr->Valid(); itr->Next()) {
     std::string key = itr->key().ToString();
     if (!StartsWithASCII(key, kDriveMetadataKeyPrefix, true))
       break;
-    std::string serialized_url(RemovePrefix(key, kDriveMetadataKeyPrefix));
+    std::string serialized_url;
+    RemovePrefix(key, kDriveMetadataKeyPrefix, &serialized_url);
 
     GURL origin;
     base::FilePath path;
     bool success = ParseV0FormatFileSystemURL(
         GURL(serialized_url), &origin, &path);
     DCHECK(success) << serialized_url;
     std::string new_key = kDriveMetadataKeyPrefix + origin.spec() +
         kMetadataKeySeparator + path.AsUTF8Unsafe();
 
     write_batch.Put(new_key, itr->value());
@@ skipping 82 matching lines @@
       continue;
     }
   }
 
   return LevelDBStatusToSyncStatusCode(
       db->Write(leveldb::WriteOptions(), &write_batch));
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system