Add CdmFileIOProvider interface for use by cdm_adapter

media/cdm/cdm_file_io.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 MEDIA_CDM_CDM_FILE_IO_H_
+#define MEDIA_CDM_CDM_FILE_IO_H_
+
+#include "base/compiler_specific.h"
+#include "base/macros.h"
+#include "media/base/media_export.h"
+#include "media/cdm/api/content_decryption_module.h"
+
+namespace media {
+
+// Implements a version of cdm::FileIO with a public destructor so it can be
+// used with std::unique_ptr.
+class MEDIA_EXPORT CdmFileIO : NON_EXPORTED_BASE(public cdm::FileIO) {
+ public:
+  ~CdmFileIO() override;
+
+ protected:
+  CdmFileIO();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CdmFileIO);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_CDM_CDM_FILE_IO_H_