Support removing b=AS bandwidth constraints.

webrtc/media/engine/webrtcmediaengine.cc

Index: webrtc/media/engine/webrtcmediaengine.cc
diff --git a/webrtc/media/engine/webrtcmediaengine.cc b/webrtc/media/engine/webrtcmediaengine.cc
index 9b5fef2478f3e26805b9959774ca45928e079796..77516b247f045574bcfd6a71f389613a0069fbe6 100644
--- a/webrtc/media/engine/webrtcmediaengine.cc
+++ b/webrtc/media/engine/webrtcmediaengine.cc
@@ -207,12 +207,9 @@ webrtc::Call::Config::BitrateConfig GetBitrateConfigForCodec(
     // Do not reconfigure start bitrate unless it's specified and positive.
     config.start_bitrate_bps = -1;
   }
-  if (codec.GetParam(kCodecParamMaxBitrate, &bitrate_kbps) &&
-      bitrate_kbps > 0) {
-    config.max_bitrate_bps = bitrate_kbps * 1000;
-  } else {
-    config.max_bitrate_bps = -1;
-  }
+  // Codec max bitrate should be set and capped by encoder config, not global
+  // bitrate config.

[Taylor Brandstetter, 2017/03/09 23:48:38]

nit: This seems independent enough to warrant being in a standalone CL.

Also, this comment is a little confusing to me. Maybe something like this would
be more clear:

"The global max bitrate should only be restricted by 'b=AS', and not by
codec-specific bitrate limits, so leave it as -1 here. The codec-specific
bitrate limits will be enforced using the encoder configuration rather than the
global BitrateConfig."

[stefan-webrtc, 2017/03/10 08:14:53]

I agree that we should do this independently. And I'm pretty sure there are
applications relying on this, which is why it hasn't been fixed yet...

Let's talk offline about what needs to be done to fix this.

[pbos-webrtc, 2017/03/10 18:52:09]

Abandoned.

+  config.max_bitrate_bps = -1;
   return config;
 }
 }  // namespace cricket