[Sync] Eliminate friends from Directory by exposing kernel via accessor

sync/syncable/directory.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 "sync/syncable/directory.h"
 
 #include <algorithm>
 #include <iterator>
 
 #include "base/base64.h"
@@ skipping 171 matching lines @@
   STLValueDeleter<MetahandlesMap> deleter(&tmp_handles_map);
 
   JournalIndex delete_journals;
   MetahandleSet metahandles_to_purge;
 
   DirOpenResult result = store_->Load(&tmp_handles_map, &delete_journals,
                                       &metahandles_to_purge, &info);
   if (OPENED != result)
     return result;
 
+  DCHECK(!kernel_);
   kernel_ = new Kernel(name, info, delegate, transaction_observer);
   delete_journal_.reset(new DeleteJournal(&delete_journals));
   InitializeIndices(&tmp_handles_map);
 
   // Write back the share info to reserve some space in 'next_id'.  This will
   // prevent local ID reuse in the case of an early crash.  See the comments in
   // TakeSnapshotForSaveChanges() or crbug.com/142987 for more information.
   kernel_->info_status = KERNEL_SHARE_INFO_DIRTY;
 
   kernel_->metahandles_to_purge.swap(metahandles_to_purge);
@@ skipping 1339 matching lines @@
   // server.  To avoid re-uploading the same attachment mulitple times, we
   // remove any ids known to be on the server from the id_set we are about to
   // return.
   //
   // TODO(maniscalco): Eliminate redundant metadata storage (bug 415203).
   std::set_difference(not_on_server_id_set.begin(), not_on_server_id_set.end(),
                       on_server_id_set.begin(), on_server_id_set.end(),
                       std::back_inserter(*ids));
 }
 
+Directory::Kernel* Directory::kernel() {
+  return kernel_;
+}
+
+const Directory::Kernel* Directory::kernel() const {
+  return kernel_;
+}
+
 }  // namespace syncable
 }  // namespace syncer