Expose codec implementation names in stats.

webrtc/modules/video_coding/include/video_coding_defines.h

Index: webrtc/modules/video_coding/include/video_coding_defines.h
diff --git a/webrtc/modules/video_coding/include/video_coding_defines.h b/webrtc/modules/video_coding/include/video_coding_defines.h
index 1b721441e241a6eb31033a8b4ae47833726c33fa..d057b554cd8fa078f3e63382d7d80694f1f562c4 100644
--- a/webrtc/modules/video_coding/include/video_coding_defines.h
+++ b/webrtc/modules/video_coding/include/video_coding_defines.h
@@ -62,6 +62,8 @@ class VCMPacketizationCallback {
                            const RTPFragmentationHeader& fragmentationHeader,
                            const RTPVideoHeader* rtpVideoHdr) = 0;
 
+  virtual void OnEncoderImplementationName(const char* implementation_name) {}
+
  protected:
   virtual ~VCMPacketizationCallback() {
   }
@@ -77,6 +79,7 @@ class VCMReceiveCallback {
   }
   // Called when the current receive codec changes.
   virtual void OnIncomingPayloadType(int payload_type) {}
+  virtual void OnDecoderImplementationName(const char* implementation_name) {}
 
  protected:
   virtual ~VCMReceiveCallback() {