Fix some grammar in sync/

sync/engine/get_commit_ids_command.h

 // 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.
 
 #ifndef SYNC_ENGINE_GET_COMMIT_IDS_COMMAND_H_
 #define SYNC_ENGINE_GET_COMMIT_IDS_COMMAND_H_
 #pragma once
 
 #include <utility>
 #include <vector>
@@ skipping 63 matching lines @@
   // present.
   // Prereq: |item| is unsynced.
   // Returns values:
   //    False: if |item| was in conflict.
   //    True: if |item| was checked for commit readiness and added to |result|
   //          as necessary.
   bool AddItem(const std::set<int64>& ready_unsynced_set,
                const syncable::Entry& item,
                sessions::OrderedCommitSet* result) const;
 
-  // Adds item and all it's unsynced predecessors to |result| as necessary, as
+  // Adds item and all its unsynced predecessors to |result| as necessary, as
   // long as no item was in conflict.
   // Return values:
   //   False: if there was an entry in conflict.
   //   True: if all entries were checked for commit readiness and added to
   //         |result| as necessary.
   bool AddItemThenPredecessors(syncable::BaseTransaction* trans,
                                const std::set<int64>& ready_unsynced_set,
                                const syncable::Entry& item,
                                sessions::OrderedCommitSet* result) const;
 
@@ skipping 22 matching lines @@
   scoped_ptr<sessions::OrderedCommitSet> ordered_commit_set_;
 
   int requested_commit_batch_size_;
 
   DISALLOW_COPY_AND_ASSIGN(GetCommitIdsCommand);
 };
 
 }  // namespace browser_sync
 
 #endif  // SYNC_ENGINE_GET_COMMIT_IDS_COMMAND_H_