sync: don't notify from ~BaseTransaction if the writer is INVALID.

chrome/browser/sync/syncable/syncable.h

 // Copyright (c) 2011 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.
 
 #ifndef CHROME_BROWSER_SYNC_SYNCABLE_SYNCABLE_H_
 #define CHROME_BROWSER_SYNC_SYNCABLE_SYNCABLE_H_
 #pragma once
 
 #include <algorithm>
 #include <bitset>
@@ skipping 1111 matching lines @@
     // unique server IDs. No need to lock, only written at init time.
     const std::string cache_guid;
 
     // It doesn't make sense for two threads to run SaveChanges at the same
     // time; this mutex protects that activity.
     base::Lock save_changes_mutex;
 
     // The next metahandle is protected by kernel mutex.
     int64 next_metahandle;
 
-    // Keep a history of recently flushed metahandles for debugging
-    // purposes.  Protected by the save_changes_mutex.
-    DebugQueue<int64, 1000> flushed_metahandles;

[rlarocque, 2011/11/15 01:08:56]

I think this is the last use of DebugQueue.  Can we delete that class, too?

-
     // The delegate for directory change events.  Can be NULL.
     DirectoryChangeDelegate* const delegate;
 
     // The transaction observers.
     scoped_refptr<ObserverListThreadSafe<TransactionObserver> > observers;
   };
 
   // Helper method used to do searches on |parent_id_child_index|.
   ParentIdChildIndex::iterator LocateInParentChildIndex(
       const ScopedKernelLock& lock,
@@ skipping 128 matching lines @@
 bool IsLegalNewParent(BaseTransaction* trans, const Id& id, const Id& parentid);
 
 // This function sets only the flags needed to get this entry to sync.
 void MarkForSyncing(syncable::MutableEntry* e);
 
 }  // namespace syncable
 
 std::ostream& operator <<(std::ostream&, const syncable::Blob&);
 
 #endif  // CHROME_BROWSER_SYNC_SYNCABLE_SYNCABLE_H_