Add PeerConnectionInterface::UpdateCallBitrate.

webrtc/call/call.h

Index: webrtc/call/call.h
diff --git a/webrtc/call/call.h b/webrtc/call/call.h
index ec73bf7714926b2a6b04210f3c66a881f9acbedf..ca6ce30c4e8d97527b7df338b25e07a9aa5ca7a6 100644
--- a/webrtc/call/call.h
+++ b/webrtc/call/call.h
@@ -75,6 +75,14 @@ class Call {
       int max_bitrate_bps = -1;
     } bitrate_config;
 
+    // TODO(zstein): Consider using PeerConnectionInterface::BitrateParameters
+    // instead (and move BitrateParameters to base/ or api/).

[Taylor Brandstetter, 2017/04/12 01:33:42]

Just FYI, it would be api/ since it's used in the API. The long term plan is for
api/ to not depend on any other directories.

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

Acknowledged.

+    struct BitrateConfigMask {
+      rtc::Optional<int> min_bitrate_bps;
+      rtc::Optional<int> start_bitrate_bps;
+      rtc::Optional<int> max_bitrate_bps;
+    };
+
     // AudioState which is possibly shared between multiple calls.
     // TODO(solenberg): Change this to a shared_ptr once we can use C++11.
     rtc::scoped_refptr<AudioState> audio_state;
@@ -136,14 +144,17 @@ class Call {
   // pacing delay, etc.
   virtual Stats GetStats() const = 0;
 
-  // TODO(pbos): Like BitrateConfig above this is currently per-stream instead
-  // of maximum for entire Call. This should be fixed along with the above.
-  // Specifying a start bitrate (>0) will currently reset the current bitrate
-  // estimate. This is due to how the 'x-google-start-bitrate' flag is currently
-  // implemented.
+  // Parameters set here are only used if they are not masked by
+  // SetBitrateConfigMask. Specifying a start bitrate (>0) will currently reset
+  // the current bitrate estimate. This is due to how the
+  // 'x-google-start-bitrate' flag is currently implemented.
   virtual void SetBitrateConfig(
       const Config::BitrateConfig& bitrate_config) = 0;
 
+  // Values set here are preferred to values set by SetBitrateConfig.
+  virtual void SetBitrateConfigMask(

[Taylor Brandstetter, 2017/04/12 01:33:42]

Just an idea/bikeshed: calling these methods something like
"SetSdpBitrateConfig" and "SetApplicationBitrateConfig" may make it more clear
what the two represent.

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

It felt wrong to talk about SDP here, so I tried to go with more generic terms.
I don't feel too strongly though.

+      const Config::BitrateConfigMask& bitrate_mask) = 0;
+
   // TODO(skvlad): When the unbundled case with multiple streams for the same
   // media type going over different networks is supported, track the state
   // for each stream separately. Right now it's global per media type.