Add codec name to CodecSpecificInfo and get the codec name stats from there instead.

BUG=webrtc:5687

Review-Url: https://codereview.webrtc.org/2253563002
Cr-Commit-Position: refs/heads/master@{#14012}

webrtc/modules/video_coding/include/video_coding_defines.h

@@ -77,9 +77,7 @@ class VCMReceiveCallback {
 // and the name of the encoder.
 class VCMSendStatisticsCallback {
  public:
-  virtual void SendStatistics(uint32_t bitRate,
-                              uint32_t frameRate,
-                              const std::string& encoder_name) = 0;
+  virtual void SendStatistics(uint32_t bitRate, uint32_t frameRate) = 0;
 
  protected:
   virtual ~VCMSendStatisticsCallback() {}