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"
+
+namespace media {
+
+// static
+const size_t DataSource::kReadError = static_cast<size_t>(-1);
+
+DataSource::DataSource() : host_(NULL) {}
+
+DataSource::~DataSource() {}
+
+void DataSource::set_host(DataSourceHost* host) { host_ = host; }

[Ami GONE FROM CHROMIUM, 2011/12/15 18:39:08]

Filter::set_host() is more DCHECK-happy.  Wanna copy that here?

[acolwell GONE FROM CHROMIUM, 2011/12/15 20:57:59]

Done.

+
+void DataSource::SetPlaybackRate(float playback_rate) {}

[Ami GONE FROM CHROMIUM, 2011/12/15 18:39:08]

I wonder if this wouldn't be better off pure-virtual.
(or at least impl'd as a NOTIMPLEMENTED if there are many derived classes, most
of which don't implement this but also expect to never have it called on them).

[acolwell GONE FROM CHROMIUM, 2011/12/15 20:57:59]

So this is another artifact of how we handle different Preroll behaviors. Really
only BufferedDataSource needs this call, but FFmpegDemuxer calls this method
independent of what DataSource we are using. I believe this method should go
away and we should implement something a little more straight forward. That is a
future CL though.

I can't change this to NOTIMPLEMENTED since I know it will get called even on
DataSources that don't care about it. Should I leave this as is or make it
pure-virtual and add empty implementations to FileDataSource & SimpleDataSource?

[Ami GONE FROM CHROMIUM, 2011/12/15 22:39:18]

I don't care.

+
+DataSourceHost* DataSource::host() { return host_; }
+
+}  // namespace media