Reland of: Adding error output param to SetConfiguration, using new RTCError type.

webrtc/media/base/mediachannel.h

Index: webrtc/media/base/mediachannel.h
diff --git a/webrtc/media/base/mediachannel.h b/webrtc/media/base/mediachannel.h
index d66424014b7cef41c41ba030f7c39c883c8b4c83..6d13e6198fd5d9812fca7713e7512fadc3195dfd 100644
--- a/webrtc/media/base/mediachannel.h
+++ b/webrtc/media/base/mediachannel.h
@@ -133,6 +133,20 @@ struct MediaConfig {
     // Enables periodic bandwidth probing in application-limited region.
     bool periodic_alr_bandwidth_probing = false;
   } video;
+
+  bool operator==(const MediaConfig& o) const {
+    return enable_dscp == o.enable_dscp &&
+           video.enable_cpu_overuse_detection ==
+               o.video.enable_cpu_overuse_detection &&
+           video.suspend_below_min_bitrate ==
+               o.video.suspend_below_min_bitrate &&
+           video.disable_prerenderer_smoothing ==
+               o.video.disable_prerenderer_smoothing &&
+           video.periodic_alr_bandwidth_probing ==
+               o.video.periodic_alr_bandwidth_probing;
+  }
+
+  bool operator!=(const MediaConfig& o) const { return !(*this == o); }
 };
 
 // Options that can be applied to a VoiceMediaChannel or a VoiceMediaEngine.