[DO NOT COMMIT] Initial MediaPlayerRenderer plumbing and basic features

media/base/android/url_demuxer_stream.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_BASE_ANDROID_URL_DEMUXER_STREAM_H_
+#define MEDIA_BASE_ANDROID_URL_DEMUXER_STREAM_H_
+
+#include <stddef.h>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "media/base/demuxer.h"
+#include "url/gurl.h"
+
+namespace media {
+
+class UrlDemuxerStream : public DemuxerStream {

[xhwang, 2016/06/22 17:39:02]

I don't feel we should have a UrlDemuxerStream. The way we use it is totally
different from a DemuxerStream, so it doesn't pass the "UrlDemuxerStream is a
DemuxerStream" test. The "NOTREACHED" in the .cc file demonstrated this as well.

Conceptually, the UrlDemuxerStreamProvider doesn't even need to be a Demuxer
either. For example, Seek() on UrlDemuxerStreamProvider doesn't make sense. But
I see that currently WMPI and Pipeline* is deeply integrated with Demuxer.
Changing that would require a much larger refactoring. So I think
UrlDemuxerStreamProvider is fine for now. In the future we can iterate on this.

With that, I wonder whether we can:

1, In DemuxerStreamProvider, in addition to GetStream(), add another method like
GetUrl(). The contract will be something like a DemuxerStreamProvider should
return non-null for GetStream() (audio and/or video), or non-empty URL for
GetUrl(), but not both.

2. Since UrlDemuxerStreamProvider is a Demuxer which is a DemuxerStreamProvider,
this should be sufficient for the Renderer to retrieve the URL.

3. With this, I feel DemuxerStreamProvider should be renamed. It's really a
"MediaSource" now, but unfortunately that name has been taken. Maybe
MediaProvider? Or anything you propose :)

+ public:
+  UrlDemuxerStream(const GURL& url);
+  virtual ~UrlDemuxerStream();
+
+  void Read(const ReadCB& read_cb) override;
+  AudioDecoderConfig audio_decoder_config() override;
+  VideoDecoderConfig video_decoder_config() override;
+  DemuxerStream::Type type() const override;
+  DemuxerStream::Liveness liveness() const override;
+  void EnableBitstreamConverter() override;
+  bool SupportsConfigChanges() override;
+  VideoRotation video_rotation() override;
+
+  GURL url() const { return url_; };
+
+ private:
+  GURL url_;
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_ANDROID_URL_DEMUXER_STREAM_PRODIVDER_H_