Prepare to remove old OnFailure implementations

This removes usage of the old OnFailure methods on CreateSessionDescriptionObserver
and SetSessionDescriptionObserver, so that WebRTC will continue to compile
once all the default implementations are removed.

Bug: chromium:589455
Change-Id: Id67295b3ad0c30d24d79589c2041acdd507a19f3
Reviewed-on: https://webrtc-review.googlesource.com/78480
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Reviewed-by: Per Kjellander <perkj@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23427}
diff --git a/examples/peerconnection/client/conductor.cc b/examples/peerconnection/client/conductor.cc
index 2483e48..746936e 100644
--- a/examples/peerconnection/client/conductor.cc
+++ b/examples/peerconnection/client/conductor.cc
@@ -45,8 +45,9 @@
         new rtc::RefCountedObject<DummySetSessionDescriptionObserver>();
   }
   virtual void OnSuccess() { RTC_LOG(INFO) << __FUNCTION__; }
-  virtual void OnFailure(const std::string& error) {
-    RTC_LOG(INFO) << __FUNCTION__ << " " << error;
+  virtual void OnFailure(webrtc::RTCError error) {
+    RTC_LOG(INFO) << __FUNCTION__ << " " << ToString(error.type()) << ": "
+                  << error.message();
   }
 };
 
@@ -545,8 +546,8 @@
   SendMessage(writer.write(jmessage));
 }
 
-void Conductor::OnFailure(const std::string& error) {
-  RTC_LOG(LERROR) << error;
+void Conductor::OnFailure(webrtc::RTCError error) {
+  RTC_LOG(LERROR) << ToString(error.type()) << ": " << error.message();
 }
 
 void Conductor::SendMessage(const std::string& json_object) {