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

webrtc/modules/video_coding/codecs/h264/h264_encoder_impl.h

Index: webrtc/modules/video_coding/codecs/h264/h264_encoder_impl.h
diff --git a/webrtc/modules/video_coding/codecs/h264/h264_encoder_impl.h b/webrtc/modules/video_coding/codecs/h264/h264_encoder_impl.h
index c6014e665183bc07ce31171b4a3e0411bb9a20c8..df7985fd388057285dac37e83213730c98dd39e0 100644
--- a/webrtc/modules/video_coding/codecs/h264/h264_encoder_impl.h
+++ b/webrtc/modules/video_coding/codecs/h264/h264_encoder_impl.h
@@ -44,7 +44,8 @@ class H264EncoderImpl : public H264Encoder {
 
   int32_t RegisterEncodeCompleteCallback(
       EncodedImageCallback* callback) override;
-  int32_t SetRates(uint32_t bitrate, uint32_t framerate) override;
+  int32_t SetRateAllocation(const BitrateAllocation& bitrate_allocation,
+                            uint32_t framerate) override;
 
   // The result of encoding - an EncodedImage and RTPFragmentationHeader - are
   // passed to the encode complete callback.