Add PeerConnectionInterface::UpdateCallBitrate.

webrtc/api/peerconnectioninterface.h

 /*
  *  Copyright 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 710 matching lines @@
       const std::vector<cricket::Candidate>& candidates) {
     return false;
   }
 
   // Register a metric observer (used by chromium).
   //
   // There can only be one observer at a time. Before the observer is
   // destroyed, RegisterUMAOberver(nullptr) should be called.
   virtual void RegisterUMAObserver(UMAObserver* observer) = 0;
 
+  // Parameters that are not set will defer to implementation defined values.

[Taylor Brandstetter, 2017/04/12 01:33:41]

"or values from x-google-[min/start/max]-bitrate, or b=AS"? Probably worth
mentioning, as long as it works that way.

[Zach Stein, 2017/04/13 00:26:36]

I was being intentionally vague to avoid this getting out of sync in the future.
I meant for implementation defined values to include all the things we do now
(static constants, SDP, and codec parameters), but I see that it would be easy
to interpret as only being constants. Can you think of a more concise way to say
"the implementation is free to choose whatever values it wants for parameters
that are not set here?"

[Taylor Brandstetter, 2017/04/13 22:16:13]

If you were being intentionally vague, "implementation defined" sounds good.

+  struct BitrateParameters {
+    rtc::Optional<int> min_bitrate_bps;
+    rtc::Optional<int> start_bitrate_bps;
+    rtc::Optional<int> max_bitrate_bps;

[Taylor Brandstetter, 2017/04/12 01:33:41]

I think it's worth describing the behavior of min/start/max at a high level
here. For example, how changes to "start" will restart bandwidth estimation (I
believe that's what we found).

[Zach Stein, 2017/04/13 00:26:36]

Done.

+  };
+
+  // Updates the Call level bitrate parameters.

[Taylor Brandstetter, 2017/04/12 01:33:41]

I wouldn't say "Call level", since someone just using the PeerConnection API
won't know what that means.

[Zach Stein, 2017/04/13 00:26:36]

Done.

+  virtual void SetCallBitrate(const BitrateParameters& bitrate) = 0;
+
   // Returns the current SignalingState.
   virtual SignalingState signaling_state() = 0;
   virtual IceConnectionState ice_connection_state() = 0;
   virtual IceGatheringState ice_gathering_state() = 0;
 
   // Starts RtcEventLog using existing file. Takes ownership of |file| and
   // passes it on to Call, which will take the ownership. If the
   // operation fails the file will be closed. The logging will stop
   // automatically after 10 minutes have passed, or when the StopRtcEventLog
   // function is called.
@@ skipping 357 matching lines @@
     cricket::WebRtcVideoEncoderFactory* encoder_factory,
     cricket::WebRtcVideoDecoderFactory* decoder_factory) {
   return CreatePeerConnectionFactory(
       worker_and_network_thread, worker_and_network_thread, signaling_thread,
       default_adm, encoder_factory, decoder_factory);
 }
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_API_PEERCONNECTIONINTERFACE_H_