[SyncFS] Fix a bug in LevelDBWrapper::Iterator::Next

chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.cc

 // Copyright 2014 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 "chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.h"
 
 #include <map>
 #include <set>
 #include <string>
 
@@ skipping 42 matching lines @@
       db_iterator_->Next();
     return;
   }
 
   if (db_iterator_->Valid()) {
     int comp = db_iterator_->key().compare(map_iterator_->first);
     if (comp <= 0)
       db_iterator_->Next();
     if (comp >= 0)
       ++map_iterator_;
+  } else {
+    ++map_iterator_;
   }
 
   AdvanceIterators();
 }
 
 leveldb::Slice LevelDBWrapper::Iterator::key() {
   DCHECK(Valid());
 
   if (!db_iterator_->Valid())
     return map_iterator_->first;
@@ skipping 117 matching lines @@
 void LevelDBWrapper::Clear() {
   pending_.clear();
 }
 
 leveldb::DB* LevelDBWrapper::GetLevelDBForTesting() {
   return db_.get();
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system