Add PacketRouter::SetMaxDesiredReceiveBitrate for application limited receive bandwidth

webrtc/modules/pacing/packet_router.h

Index: webrtc/modules/pacing/packet_router.h
diff --git a/webrtc/modules/pacing/packet_router.h b/webrtc/modules/pacing/packet_router.h
index e5abdeb2ab18e2dec47ec4734aa44720bc4f65a1..71382be628970e2bd015992f73418ded1ee8bed1 100644
--- a/webrtc/modules/pacing/packet_router.h
+++ b/webrtc/modules/pacing/packet_router.h
@@ -83,6 +83,10 @@ class PacketRouter : public PacedSender::PacketSender,
   void OnReceiveBitrateChanged(const std::vector<uint32_t>& ssrcs,
                                uint32_t bitrate_bps) override;
 
+  // Configures max bitrate application would like to receive.
+  // Ensures remote party notified of the estimate no larger than |bitrate_bps|.

[eladalon, 2017/08/04 08:32:49]

I find this a bit confusing. It's not easy to find a better wording that doesn't
become too long, though. I suggest - and this is just a nit - to let the reader
figure out what REMB is using other comments in this file, and here only write:
// Cap the estimate sent to the other side.
// If [fill in here], a new REMB message will be produced immediately.

[danilchap, 2017/08/04 10:51:23]

Rephrased a bit hoping to reduce confusion. (estimate -> receive bitrate limit)

Would like to avoid be too specific about the current implementation.
https://google.github.io/styleguide/cppguide.html#Function_Comments
"Declaration comments describe use of the function"
e.g. it might make sense to notify using tmmbr instead of remb.

+  void SetMaxEstimatedBandwidth(uint32_t bitrate_bps);

[stefan-webrtc, 2017/08/04 08:58:14]

Isn't it better to give this a name that reflects what it's used for? E.g.,
SetMaxDesiredReceiveBitrate()

[danilchap, 2017/08/04 10:51:23]

Done. That looks better, thank you.

+
   // Send REMB feedback.
   virtual bool SendRemb(uint32_t bitrate_bps,
                         const std::vector<uint32_t>& ssrcs);
@@ -111,6 +115,7 @@ class PacketRouter : public PacedSender::PacketSender,
   uint32_t last_send_bitrate_bps_ GUARDED_BY(remb_crit_);
   // The last bitrate update.
   uint32_t bitrate_bps_ GUARDED_BY(remb_crit_);
+  uint32_t max_bitrate_bps_ GUARDED_BY(remb_crit_);
 
   // Candidates for the REMB module can be RTP sender/receiver modules, with
   // the sender modules taking precedence.