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

webrtc/modules/video_coding/video_coding_impl.h

Index: webrtc/modules/video_coding/video_coding_impl.h
diff --git a/webrtc/modules/video_coding/video_coding_impl.h b/webrtc/modules/video_coding/video_coding_impl.h
index cb24654041aeb4a7e186f74ebe49c624167cd1f6..053363454610cfdea6235f8903e2c5ce28e7b2b4 100644
--- a/webrtc/modules/video_coding/video_coding_impl.h
+++ b/webrtc/modules/video_coding/video_coding_impl.h
@@ -34,6 +34,8 @@
 
 namespace webrtc {
 
+class VideoBitrateAllocator;
+
 namespace vcm {
 
 class VCMProcessTimer {
@@ -75,9 +77,15 @@ class VideoSender : public Module {
   int Bitrate(unsigned int* bitrate) const;
   int FrameRate(unsigned int* framerate) const;
 
-  int32_t SetChannelParameters(uint32_t target_bitrate,  // bits/s.
+  int32_t SetChannelParameters(uint32_t target_bitrate_bps,
                                uint8_t lossRate,
-                               int64_t rtt);
+                               int64_t rtt,
+                               VideoBitrateAllocator* bitrate_allocator);
+  // Calls SetChannelParameters(), with the previous target bitrate, loss rate
+  // and RTT, but reallocates the bitrate allocation based on a presumably
+  // updated codec configuration.
+  int32_t UpdateChannelParemeters(VideoBitrateAllocator* bitrate_allocator);
+
   // Deprecated:
   // TODO(perkj): Remove once no projects use it.
   int32_t RegisterProtectionCallback(VCMProtectionCallback* protection);