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

webrtc/modules/video_coding/video_coding_impl.cc

Index: webrtc/modules/video_coding/video_coding_impl.cc
diff --git a/webrtc/modules/video_coding/video_coding_impl.cc b/webrtc/modules/video_coding/video_coding_impl.cc
index 2f709b610c1453a6e8fc9415042189a9f03ddae2..addf124a6f623fc4ef3ef6284612196a26f3e3d8 100644
--- a/webrtc/modules/video_coding/video_coding_impl.cc
+++ b/webrtc/modules/video_coding/video_coding_impl.cc
@@ -125,8 +125,10 @@ class VideoCodingModuleImpl : public VideoCodingModule {
 
   int32_t SetChannelParameters(uint32_t target_bitrate,  // bits/s.
                                uint8_t lossRate,
-                               int64_t rtt) override {
-    return sender_.SetChannelParameters(target_bitrate, lossRate, rtt);
+                               int64_t rtt,
+                               VideoBitrateAllocator* allocator) override {
+    return sender_.SetChannelParameters(target_bitrate, lossRate, rtt,
+                                        allocator);
   }
 
   int32_t RegisterProtectionCallback(