Revert of Remove AudioTrackRenderer

talk/media/base/fakemediaengine.h

Index: talk/media/base/fakemediaengine.h
diff --git a/talk/media/base/fakemediaengine.h b/talk/media/base/fakemediaengine.h
index e5c4c5324154ef58d3ed8e6f23f694792b222bad..7325667aa544568cf29199af4736e5f6c6ffb519 100644
--- a/talk/media/base/fakemediaengine.h
+++ b/talk/media/base/fakemediaengine.h
@@ -308,9 +308,11 @@
         ASSERT(it->second == renderer);
       } else {
         remote_renderers_.insert(std::make_pair(ssrc, renderer));
+        renderer->AddChannel(0);
       }
     } else {
       if (it != remote_renderers_.end()) {
+        it->second->RemoveChannel(0);
         remote_renderers_.erase(it);
       } else {
         return false;
@@ -380,10 +382,12 @@
    public:
     explicit VoiceChannelAudioSink(AudioRenderer* renderer)
         : renderer_(renderer) {
+      renderer_->AddChannel(0);
       renderer_->SetSink(this);
     }
     virtual ~VoiceChannelAudioSink() {
       if (renderer_) {
+        renderer_->RemoveChannel(0);
         renderer_->SetSink(NULL);
       }
     }