Add task queue to Call.

webrtc/config.h

Index: webrtc/config.h
diff --git a/webrtc/config.h b/webrtc/config.h
index 1550a9f8a13ac1b121c90b31a771eee56e12f1a6..d932eda1df8eee81a3d004518fcc9396a495d2c2 100644
--- a/webrtc/config.h
+++ b/webrtc/config.h
@@ -125,12 +125,20 @@ struct VideoStream {
 };
 
 struct VideoEncoderConfig {
+ public:
   enum class ContentType {
     kRealtimeVideo,
     kScreen,
   };
 
+  VideoEncoderConfig& operator=(VideoEncoderConfig&&) = default;
+  VideoEncoderConfig& operator=(const VideoEncoderConfig&) = delete;
+
+  // Mostly used by tests.  Avoid creating copies if you can.
+  VideoEncoderConfig Copy() const { return VideoEncoderConfig(*this); }
+
   VideoEncoderConfig();
+  VideoEncoderConfig(VideoEncoderConfig&&) = default;
   ~VideoEncoderConfig();
   std::string ToString() const;
 
@@ -145,6 +153,11 @@ struct VideoEncoderConfig {
   // unless the estimated bandwidth indicates that the link can handle it.
   int min_transmit_bitrate_bps;
   bool expect_encode_from_texture;
+
+ private:
+  // Access to the copy constructor is private to force use of the Copy()
+  // method for those exceptional cases where we do use it.
+  VideoEncoderConfig(const VideoEncoderConfig&) = default;
 };
 
 struct VideoDecoderH264Settings {