[LevelDBWrapper] Fix an issue that check condition is always true.

content/browser/leveldb_wrapper_impl.cc

 // Copyright 2016 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 "content/browser/leveldb_wrapper_impl.h"
 
 #include "base/bind.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "content/public/browser/browser_thread.h"
 #include "mojo/common/common_type_converters.h"
@@ skipping 317 matching lines @@
     leveldb::mojom::BatchedOperationPtr item =
         leveldb::mojom::BatchedOperation::New();
     item->type = leveldb::mojom::BatchOperationType::DELETE_PREFIXED_KEY;
     item->key = mojo::Array<uint8_t>::From(std::string(prefix_));
     operations.push_back(std::move(item));
   }
   for (auto& it : commit_batch_->changed_values) {
     leveldb::mojom::BatchedOperationPtr item =
         leveldb::mojom::BatchedOperation::New();
     item->key = it.first.Clone();
-    if (item->value.is_null()) {
+    if (it.second.is_null()) {
       item->type = leveldb::mojom::BatchOperationType::DELETE_KEY;
     } else {
       item->type = leveldb::mojom::BatchOperationType::PUT_KEY;
       item->value = std::move(it.second);
     }
     operations.push_back(std::move(item));
   }
   commit_batch_.reset();
 
   ++commit_batches_in_flight_;
 
   // TODO(michaeln): Currently there is no guarantee LevelDBDatabaseImp::Write
   // will run during a clean shutdown. We need that to avoid dataloss.
   database_->Write(std::move(operations),
                    base::Bind(&LevelDBWrapperImpl::OnCommitComplete,
                               weak_ptr_factory_.GetWeakPtr()));
 }
 
 void LevelDBWrapperImpl::OnCommitComplete(leveldb::mojom::DatabaseError error) {
   // TODO(michaeln): What if it fails, uma here or in the DB class?
   --commit_batches_in_flight_;
   StartCommitTimer();
 }
 
 }  // namespace content