drive: Do not clear dirty bit if someone is writing to the file

chrome/browser/chromeos/drive/file_system/update_operation.cc

 // 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.
 
 #include "chrome/browser/chromeos/drive/file_system/update_operation.h"
 
 #include "base/platform_file.h"
 #include "chrome/browser/chromeos/drive/drive.pb.h"
 #include "chrome/browser/chromeos/drive/file_cache.h"
 #include "chrome/browser/chromeos/drive/file_system/operation_observer.h"
@@ skipping 77 matching lines @@
   entry.set_parent_local_id(existing_entry.parent_local_id());
 
   error = metadata->RefreshEntry(entry);
   if (error != FILE_ERROR_OK)
     return error;
 
   *drive_file_path = metadata->GetFilePath(local_id);
   if (drive_file_path->empty())
     return FILE_ERROR_NOT_FOUND;
 
-  // Clear the dirty bit if we have updated an existing file.
+  // Do not clear the dirty bit if someone is writing to the file.
+  if (cache->IsOpenedForWrite(local_id))
+    return FILE_ERROR_OK;
   return cache->ClearDirty(local_id, entry.file_specific_info().md5());
 }
 
 }  // namespace
 
 UpdateOperation::UpdateOperation(
     base::SequencedTaskRunner* blocking_task_runner,
     OperationObserver* observer,
     JobScheduler* scheduler,
     internal::ResourceMetadata* metadata,
@@ skipping 102 matching lines @@
   if (error != FILE_ERROR_OK) {
     callback.Run(error);
     return;
   }
   observer_->OnDirectoryChangedByOperation(drive_file_path->DirName());
   callback.Run(FILE_ERROR_OK);
 }
 
 }  // namespace file_system
 }  // namespace drive