Get VideoCapturer stats via VideoTrackSourceInterface in StatsCollector,

webrtc/api/mediastreaminterface.h

Index: webrtc/api/mediastreaminterface.h
diff --git a/webrtc/api/mediastreaminterface.h b/webrtc/api/mediastreaminterface.h
index 3e79b94f9efd7e7f143d09ddb50f269f8702e0e4..7c0d82a13689b36f0bd6f83518909e71ba8d67ad 100644
--- a/webrtc/api/mediastreaminterface.h
+++ b/webrtc/api/mediastreaminterface.h
@@ -87,6 +87,10 @@ class MediaStreamTrackInterface : public rtc::RefCountInterface,
   static const char kAudioKind[];
   static const char kVideoKind[];
 
+  // The kind() method must return kAudioKind only if the object is a
+  // subclass of AudioTrackInterface, and kVideoKind only if the
+  // object is a subclass of VideoTrackInterface. It is typically used
+  // to protect a static_cast<> to the corresponding subclass.
   virtual std::string kind() const = 0;
   virtual std::string id() const = 0;
   virtual bool enabled() const = 0;
@@ -103,6 +107,11 @@ class VideoTrackSourceInterface
     : public MediaSourceInterface,
       public rtc::VideoSourceInterface<cricket::VideoFrame> {
  public:
+  struct Stats {
+    // Original frame size, before video adaptation.
+    int input_width;
+    int input_height;
+  };
   // Get access to the source implementation of cricket::VideoCapturer.
   // This can be used for receiving frames and state notifications.
   // But it should not be used for starting or stopping capturing.
@@ -127,6 +136,8 @@ class VideoTrackSourceInterface
   // the encoder.
   virtual bool needs_denoising() const = 0;
 
+  virtual bool GetStats(Stats* stats) = 0;

[pbos-webrtc, 2016/03/31 11:50:46]

I assume this is intended to fail if we haven't gotten a first frame? Can you
document when GetStats would be expected to fail?

Otherwise: Can this be void instead?

[perkj_webrtc, 2016/03/31 11:57:30]

prefer void.

[nisse-webrtc, 2016/03/31 12:07:27]

What should a VideoTrackSource (used for remote sources) do then?

[nisse-webrtc, 2016/03/31 12:07:27]

It's intended to fail if the source doesn't have any stats. In particular, a
remote source will always return false.

[perkj_webrtc, 2016/03/31 12:13:31]

I see. Ok - please then document when this returns true/false.

+
  protected:
   virtual ~VideoTrackSourceInterface() {}
 };