Connect webrtc MediaSourceInterface ready states with webkit WebMediaStreamSource

content/renderer/media/media_stream_source_observer.h

+// Copyright (c) 2013 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 CONTENT_RENDERER_MEDIA_MEDIA_STREAM_SOURCE_OBSERVER_H_
+#define CONTENT_RENDERER_MEDIA_MEDIA_STREAM_SOURCE_OBSERVER_H_
+
+#include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
+#include "base/threading/non_thread_safe.h"
+#include "content/common/content_export.h"
+#include "third_party/libjingle/source/talk/app/webrtc/mediastreaminterface.h"
+#include "third_party/WebKit/Source/Platform/chromium/public/WebMediaStreamSource.h"
+
+namespace content {
+
+// MediaStreamSourceObserver listens to events on MediaSourceInterface and
+// notify WebKit. It will be owned by MediaStreamSourceExtraData.
+//
+// This will create circular reference to MediaStreamSource:
+// MediaStreamSource -> MediaStreamSourceExtraData -> MediaStreamSourceObserver
+// -> MediaStreamSource
+// Currently, it relies on manually releasing the reference count, like what
+// ~UserMediaRequestInfo() does.
+// TODO(kcwu): fix the circular reference after ExtraData::Owner() is
+// implemented, which let us get MediaStreamSource without increasing reference
+// count.
+class CONTENT_EXPORT MediaStreamSourceObserver
+    : NON_EXPORTED_BASE(public webrtc::ObserverInterface),
+      NON_EXPORTED_BASE(public base::NonThreadSafe) {
+ public:
+  MediaStreamSourceObserver(webrtc::MediaSourceInterface* webrtc_source,
+                            const WebKit::WebMediaStreamSource& webkit_source);

[perkj_chrome, 2013/04/18 13:36:20]

How about preparing for  ExtraData::Owner()  ? 

const WebKit::WebMediaStreamSource& ExtraData::Owner() is landed?

Ie- let the ctor take a pointer to MediaStreamSourceExtraData as argument
instead of |webkit_source|.

Add a method MediaStreamSourceExtraData::Owner that returns 
|webkit_source_|.

That way you will not have to change this class (or at least minimal) once
::Owner is landed.

This is just a suggestion- if you rather want to do this change later I am ok
with it.

+  virtual ~MediaStreamSourceObserver();
+
+  // webrtc::ObserverInterface implementation.
+  virtual void OnChanged() OVERRIDE;
+
+ private:
+  webrtc::MediaSourceInterface::SourceState state_;
+  scoped_refptr<webrtc::MediaSourceInterface> webrtc_source_;
+  WebKit::WebMediaStreamSource webkit_source_;
+
+  DISALLOW_COPY_AND_ASSIGN(MediaStreamSourceObserver);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_MEDIA_MEDIA_STREAM_SOURCE_OBSERVER_H_