Add CdmFileIOProvider interface for use by cdm_adapter

media/cdm/simple_cdm_file_io_provider.cc

+// 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.
+
+#include "media/cdm/simple_cdm_file_io_provider.h"
+
+namespace media {
+
+SimpleCdmFileIOProvider::SimpleCdmFileIOProvider() {}
+
+SimpleCdmFileIOProvider::~SimpleCdmFileIOProvider() {}
+
+// For testing we don't use FileIO, so simply return NULL.
+cdm::FileIO* SimpleCdmFileIOProvider::CreateFileIO(cdm::FileIOClient* client) {
+  return nullptr;
+}
+
+}  // namespace media