Removing DataSource from Filter hierarchy

media/base/data_source.cc

+// Copyright (c) 2011 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/base/data_source.h"
+
+#include "base/logging.h"
+
+namespace media {
+
+// static
+const size_t DataSource::kReadError = static_cast<size_t>(-1);
+
+DataSourceHost::~DataSourceHost() {}
+
+DataSource::DataSource() : host_(NULL) {}
+
+DataSource::~DataSource() {}
+
+void DataSource::set_host(DataSourceHost* host) {
+  DCHECK(host);
+  DCHECK(!host_);
+  host_ = host;
+}
+
+void DataSource::SetPlaybackRate(float playback_rate) {}
+
+DataSourceHost* DataSource::host() { return host_; }
+
+}  // namespace media