drive: Remove obsolete comment from drive.proto

chrome/browser/chromeos/drive/drive.proto

 // Copyright (c) 2012 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.
 //
 // Protocol buffer definitions for representing Drive files and directories,
 // and serializing them for the resource metadata database.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
@@ skipping 85 matching lines @@
 message ResourceMetadataHeader {
   // Monotonically increasing version number, which is changed when
   // incompatible change is made to the DB format. kDBVersion in
   // drive_resource_metadata_storage.h defines the current version.
   optional int32 version = 1;
   optional int64 largest_changestamp = 2;
 }
 
 // Message to store information of an existing cache file.
 message FileCacheEntry {
-  // MD5 of the cache file. "local" if the file is locally modified.
+  // MD5 of the cache file.
   optional string md5 = 1;
 
   // True if the file is present locally.
   optional bool is_present = 2;
 
   // True if the file is pinned (i.e. available offline).
   optional bool is_pinned = 3;
 
   // True if the file is dirty (i.e. modified locally).
   optional bool is_dirty = 4;
 
-  // TODO(hashimoto): Remove this block after DB merge. crbug.com/234487
-  // True if the file is in the persistent directory.
-  // optional bool is_persistent = 6;
-
   // When adding a new state, be sure to update TestFileCacheState and test
-  // functions defined in drive_test_util.cc.
+  // functions defined in test_util.cc.
 }