Define EncodedVideoSource and RtcCapturedEncodingVideoCapturer.

content/renderer/media/video_capture_impl_manager.h

 // Copyright (c) 2012 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.
 
 // VideoCaptureImplManager manages video capture devices in renderer process.
 // The video capture clients use AddDevice() to get a pointer to
 // video capture device. VideoCaputreImplManager supports multiple clients
 // accessing same device.
 
 #ifndef CONTENT_RENDERER_MEDIA_VIDEO_CAPTURE_IMPL_MANAGER_H_
 #define CONTENT_RENDERER_MEDIA_VIDEO_CAPTURE_IMPL_MANAGER_H_
 
 #include <list>
 #include <map>
 
 #include "base/threading/thread.h"
 #include "base/message_loop_proxy.h"
 #include "base/synchronization/lock.h"
 #include "content/common/content_export.h"
 #include "media/video/capture/video_capture.h"
+#include "media/video/encoded_video_source.h"
 
 namespace content {
 
+class RtcEncodingVideoCapturerFactory;
 class VideoCaptureImpl;
 class VideoCaptureMessageFilter;
 
 class CONTENT_EXPORT VideoCaptureImplManager
     : public base::RefCountedThreadSafe<VideoCaptureImplManager> {
  public:
   VideoCaptureImplManager();
 
   // Called by video capture client |handler| to add device referenced
   // by |id| to VideoCaptureImplManager's list of opened device list.
   // A pointer to VideoCapture is returned to client so that client can
   // operate on that pointer, such as StartCaptrue, StopCapture.
   virtual media::VideoCapture* AddDevice(
       media::VideoCaptureSessionId id,
       media::VideoCapture::EventHandler* handler);
 
   // Called by video capture client |handler| to remove device referenced
   // by |id| from VideoCaptureImplManager's list of opened device list.
   virtual void RemoveDevice(media::VideoCaptureSessionId id,
                             media::VideoCapture::EventHandler* handler);
 
   // Make all existing VideoCaptureImpl instances stop/resume delivering
   // video frames to their clients, depends on flag |suspend|.
   virtual void SuspendDevices(bool suspend);
 
   VideoCaptureMessageFilter* video_capture_message_filter() const {
     return filter_.get();
   }
 
+  RtcEncodingVideoCapturerFactory* encoding_capturer_factory() const {

[Ami GONE FROM CHROMIUM, 2013/06/08 00:18:01]

It's almost never a good idea to return a raw pointer to an object whose
lifetime is governed by a scoped_refptr<>.

[hshi1, 2013/06/12 00:50:24]

The problem I'm facing is that the factory pointer is supposed to be owned by
the PeerConnectionFactory (which is the pc_factory_ member of
MediaStreamDependencyFactory). In the current libjingle design, factory lives in
a talk_base::scoped_ptr in pc_factory_. So, it seems wrong to also hold
encoding_capturer_factory_ in a scoped_refptr of vc_manager_. Furthermore, I
believe the vc_manager_ outlives the pc_factory_ (the latter is owned by
MediaStreamDependencyFactory which is outlived by vc_manager_), so we need to
avoid vc_manager_ using the encoder_factory_ after pc_factory_ is freed in
MediaStreamDependencyFactory::CleanupPeerConnectionFactory().

Would the following work?
(1) vc_manager_ ctor constructs and holds a (not scoped) pointer to
encoder_factory_, and pass itself to encoder_factory_;
(2) at CPCF, the encoder_factory_ is passed to the PC factory;
(3) the dtor of encoder_factory_ notifies vc_manager_ that it is destroyed.
After that vc_manager_ will clear the pointer and no longer call
encoder_factory_ when video capturer impls are added/removed.

[hshi1, 2013/06/13 22:03:46]

I've made the following change:
(1) the encoding_capturer_factory is now created by
MediaStreamDependencyFactory, then passed to and owned by its
PeerConnectionFactory;
(2) VCImplManager receives a weak pointer to the factory. VCImplManager will
outlive the PeerConnectionFactory.

+    return encoding_capturer_factory_.get();
+  }
+
  protected:
   virtual ~VideoCaptureImplManager();
 
  private:
   friend class base::RefCountedThreadSafe<VideoCaptureImplManager>;
 
   struct Device {
     Device(VideoCaptureImpl* device,
            media::VideoCapture::EventHandler* handler);
     ~Device();
 
     VideoCaptureImpl* vc;
     std::list<media::VideoCapture::EventHandler*> clients;
   };
 
   void FreeDevice(VideoCaptureImpl* vc);
 
   typedef std::map<media::VideoCaptureSessionId, Device*> Devices;
   Devices devices_;
   base::Lock lock_;
   scoped_refptr<VideoCaptureMessageFilter> filter_;
   base::Thread thread_;
   scoped_refptr<base::MessageLoopProxy> message_loop_proxy_;
 
+  scoped_refptr<RtcEncodingVideoCapturerFactory> encoding_capturer_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(VideoCaptureImplManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_VIDEO_CAPTURE_IMPL_MANAGER_H_