Fix and refactor downloaded file handling in the loading stack

content/browser/loader/downloaded_temp_file_impl.h

+// 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.
+
+#ifndef CONTENT_BROWSER_LOADER_DOWNLOADED_TEMP_FILE_IMPL_H_
+#define CONTENT_BROWSER_LOADER_DOWNLOADED_TEMP_FILE_IMPL_H_
+
+#include "base/macros.h"
+#include "content/common/content_export.h"
+#include "content/common/url_loader_factory.mojom.h"
+
+namespace content {
+
+// DownloadedTempFileImpl is created on the download_to_file mode of resource
+// loading. The instance is held by the client and lives until the client
+// destroys the interface, slightly after the URLLoader is destroyed.
+class CONTENT_EXPORT DownloadedTempFileImpl final
+    : public mojom::DownloadedTempFile {
+ public:
+  static mojo::InterfacePtr<mojom::DownloadedTempFile> Create(int child_id,
+                                                              int request_id);
+
+  DownloadedTempFileImpl(int child_id, int request_id);
+  ~DownloadedTempFileImpl() override;
+
+ private:
+  int child_id_;
+  int request_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(DownloadedTempFileImpl);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_LOADER_DOWNLOADED_TEMP_FILE_IMPL_H_