Make fec controller plug-able.

Bug: webrtc:8656
Change-Id: I3d42ffc92a7c95266e5d53bab03f388bd0de2592
Reviewed-on: https://webrtc-review.googlesource.com/39760
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Commit-Queue: Ying Wang <yinwa@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21710}

modules/video_coding/include/video_coding_defines.h

@@ -108,20 +108,6 @@ class VCMReceiveStatisticsCallback {
   virtual ~VCMReceiveStatisticsCallback() {}
 };
 
-// Callback class used for telling the user about how to configure the FEC,
-// and the rates sent the last second is returned to the VCM.
-class VCMProtectionCallback {
- public:
-  virtual int ProtectionRequest(const FecProtectionParams* delta_params,
-                                const FecProtectionParams* key_params,
-                                uint32_t* sent_video_rate_bps,
-                                uint32_t* sent_nack_rate_bps,
-                                uint32_t* sent_fec_rate_bps) = 0;
-
- protected:
-  virtual ~VCMProtectionCallback() {}
-};
-
 // Callback class used for telling the user about what frame type needed to
 // continue decoding.
 // Typically a key frame when the stream has been corrupted in some way.