media: Verify CDM Host files

content/common/media/cdm_host_file.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_COMMON_MEDIA_CDM_HOST_FILE_H_
+#define CONTENT_COMMON_MEDIA_CDM_HOST_FILE_H_
+
+#include <memory>
+
+#include "base/files/file.h"
+#include "base/files/file_path.h"
+#include "base/macros.h"
+
+namespace cdm {
+struct HostFile;
+}
+
+namespace content {
+
+// Represents a file that participated in hosting the CDM.
+class CdmHostFile {
+ public:
+  // Opens the file at |file_path| and the corresponding signature file at
+  // |sig_file_path|. Upon success, constructs and returns a CdmHostFile object.
+  // Otherwise returns nullptr. The opened files are closed when |this| is
+  // destructed unless TakePlatformFile() was called, in which case the caller
+  // must make sure the files are closed properly.
+  static std::unique_ptr<CdmHostFile> Create(
+      const base::FilePath& file_path,
+      const base::FilePath& sig_file_path);
+
+  // Takes the PlatformFile of the |file_| and |sig_file_| and put them in the
+  // returned cdm::HostFile. The caller must make sure the PlatformFiles are
+  // properly closed after use.
+  cdm::HostFile TakePlatformFile();

[Greg K, 2017/01/19 04:13:07]

cdm::HostFile and CdmHostFile seems confusing to read, but maybe the other
reviewers are OK with the naming.

[xhwang, 2017/01/19 08:30:50]

Acknowledged.

+
+ private:
+  CdmHostFile(const base::FilePath& file_path,
+              base::File file,
+              base::File sig_file);
+
+  base::FilePath file_path_;
+  base::File file_;
+
+  // The signature file associated with |file_|.
+  base::File sig_file_;
+
+  DISALLOW_COPY_AND_ASSIGN(CdmHostFile);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_COMMON_MEDIA_CDM_HOST_FILE_H_