drive: Remove obsolete comment from drive.proto

chrome/browser/chromeos/drive/drive.proto

Index: chrome/browser/chromeos/drive/drive.proto
diff --git a/chrome/browser/chromeos/drive/drive.proto b/chrome/browser/chromeos/drive/drive.proto
index 5eef041cdca22d58a96c57457963aa0997c514fc..9d51409005da87eb0f7834661a507db9e1a94c2a 100644
--- a/chrome/browser/chromeos/drive/drive.proto
+++ b/chrome/browser/chromeos/drive/drive.proto
@@ -103,7 +103,7 @@ message ResourceMetadataHeader {
 
 // 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.
@@ -115,10 +115,6 @@ message FileCacheEntry {
   // 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.
 }