[Sync] Don't commit items with predecessors/parents in conflict.

chrome/browser/sync/sessions/ordered_commit_set.h

 // Copyright (c) 2010 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_SESSIONS_ORDERED_COMMIT_SET_H_
 #define CHROME_BROWSER_SYNC_SESSIONS_ORDERED_COMMIT_SET_H_
 #pragma once
 
 #include <map>
 #include <set>
@@ skipping 58 matching lines @@
   }
 
   int Size() const {
     return commit_ids_.size();
   }
 
   // Returns true iff any of the commit ids added to this set have model type
   // BOOKMARKS.
   bool HasBookmarkCommitId() const;
 
+  void Append(const OrderedCommitSet& other);
   void AppendReverse(const OrderedCommitSet& other);
   void Truncate(size_t max_size);
 
   void operator=(const OrderedCommitSet& other);
  private:
   // A set of CommitIdProjections associated with particular ModelSafeGroups.
   typedef std::map<browser_sync::ModelSafeGroup, Projection> Projections;
 
   // Helper container for return value of GetCommitItemAt.
   struct CommitItem {
@@ skipping 20 matching lines @@
   std::vector<syncable::ModelType> types_;
 
   browser_sync::ModelSafeRoutingInfo routes_;
 };
 
 }  // namespace sessions
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_SESSIONS_ORDERED_COMMIT_SET_H_