Move MTPDeviceDelegateImplLinux worker classes to its own files.

chrome/browser/media_gallery/linux/mtp_device_operations_utils.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.
+
+// MTPDeviceOperationsUtils provides support to media transfer protocol device
+// file operation worker classes.
+
+#ifndef CHROME_BROWSER_MEDIA_GALLERY_LINUX_MTP_DEVICE_OPERATIONS_UTILS_H_
+#define CHROME_BROWSER_MEDIA_GALLERY_LINUX_MTP_DEVICE_OPERATIONS_UTILS_H_
+
+#include "base/location.h"
+#include "base/logging.h"
+#include "base/sequenced_task_runner.h"
+#include "base/sequenced_task_runner_helpers.h"
+#include "base/threading/sequenced_worker_pool.h"
+
+namespace chrome {
+
+class MediaTransferProtocolManager;
+
+// Helper struct to delete worker objects on |media_task_runner_| thread.
+template <typename WORKER> struct WorkerDeleter {
+  static void Destruct(const WORKER* worker) {
+    if (!worker->media_task_runner()->RunsTasksOnCurrentThread()) {
+      worker->media_task_runner()->DeleteSoon(FROM_HERE, worker);
+      return;
+    }
+    delete worker;
+  }
+};
+
+// Returns MediaTransferProtocolManager instance on success or NULL on failure.
+MediaTransferProtocolManager* GetMediaTransferProtocolManager();
+
+}  // namespace chrome
+
+#endif  // CHROME_BROWSER_MEDIA_GALLERY_LINUX_MTP_DEVICE_OPERATIONS_UTILS_H_