Extract bitrate allocation of spatial/temporal layers out of codec impl.

webrtc/modules/video_coding/codecs/i420/include/i420.h

Index: webrtc/modules/video_coding/codecs/i420/include/i420.h
diff --git a/webrtc/modules/video_coding/codecs/i420/include/i420.h b/webrtc/modules/video_coding/codecs/i420/include/i420.h
index 220aea4b86f3cdcd26f2e0fcf3fcf71cecc08474..38dcafd0c339a1d342c24a2e3b4beef113e2b75a 100644
--- a/webrtc/modules/video_coding/codecs/i420/include/i420.h
+++ b/webrtc/modules/video_coding/codecs/i420/include/i420.h
@@ -13,6 +13,7 @@
 
 #include <vector>
 
+#include "webrtc/base/checks.h"
 #include "webrtc/modules/video_coding/include/video_codec_interface.h"
 #include "webrtc/typedefs.h"
 
@@ -65,10 +66,6 @@ class I420Encoder : public VideoEncoder {
   // Return value                : WEBRTC_VIDEO_CODEC_OK if OK, < 0 otherwise.
   int Release() override;
 
-  int SetRates(uint32_t /*newBitRate*/, uint32_t /*frameRate*/) override {
-    return WEBRTC_VIDEO_CODEC_OK;
-  }
-
   int SetChannelParameters(uint32_t /*packetLoss*/, int64_t /*rtt*/) override {
     return WEBRTC_VIDEO_CODEC_OK;
   }