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/files/file_path.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "content/common/content_export.h"
+#include "content/common/url_loader_factory.mojom.h"
+#include "mojo/public/cpp/bindings/binding.h"
+
+namespace storage {
+class ShareableFileReference;
+}
+
+namespace content {
+
+class ResourceDispatcherHostImpl;
+
+// DownloadedTempFileImpl is created on the download_to_file mode of resource
+// loading. The instance is held by ResourceDispatcherHostImpl and slightly
+// outlives URLLoader until the client destroyes the interface.

[dcheng, 2016/11/17 11:16:02]

Nit: destroys

[mmenke, 2016/11/17 16:59:33]

"outlives until" isn't grammatically correct.  Maybe ".... outlives URLLoader,
and is torn down when client destroys" or "and lives until the client destroys
the interface, slightly after the URLLoader is destroyed."

[mmenke, 2016/11/17 16:59:33]

"URLLoader"?  This is also used on the non-Mojo path, which doesn't use a
URLLoader.

[tzik, 2016/11/22 13:54:45]

Done.

+class CONTENT_EXPORT DownloadedTempFileImpl final
+    : public mojom::DownloadedTempFile {
+ public:
+  DownloadedTempFileImpl(ResourceDispatcherHostImpl* rdh,
+                         int child_id,
+                         int request_id,
+                         const base::FilePath& path);
+  ~DownloadedTempFileImpl() override;
+
+  mojo::InterfacePtr<mojom::DownloadedTempFile> CreateInterfacePtrAndBind();
+
+  int child_id() const { return child_id_; }
+  int request_id() const { return request_id_; }

[mmenke, 2016/11/17 16:59:33]

Not actually used?  (Well, it's used in RDH, but nothing is done with it)

+  const scoped_refptr<storage::ShareableFileReference>& reference() const {
+    return reference_;
+  }
+
+ private:
+  void OnConnectionError();
+
+  mojo::Binding<DownloadedTempFile> binding_;
+
+  ResourceDispatcherHostImpl* rdh_;
+  int child_id_;
+  int request_id_;
+
+  scoped_refptr<storage::ShareableFileReference> reference_;
+
+  DISALLOW_COPY_AND_ASSIGN(DownloadedTempFileImpl);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_LOADER_DOWNLOADED_TEMP_FILE_IMPL_H_