[Cast Channel] Add support for nonce challenge to Cast channel authentication.

extensions/browser/api/cast_channel/cast_socket_unittest.cc

Index: extensions/browser/api/cast_channel/cast_socket_unittest.cc
diff --git a/extensions/browser/api/cast_channel/cast_socket_unittest.cc b/extensions/browser/api/cast_channel/cast_socket_unittest.cc
index 48e60c83a6bcac8103a807fdfb9c3ab073fb5bb8..15a21a6070d08257af1ec9cc64a2e9caadacb703 100644
--- a/extensions/browser/api/cast_channel/cast_socket_unittest.cc
+++ b/extensions/browser/api/cast_channel/cast_socket_unittest.cc
@@ -60,7 +60,8 @@ const char kAuthNamespace[] = "urn:x-cast:com.google.cast.tp.deviceauth";
 // Returns an auth challenge message inline.
 CastMessage CreateAuthChallenge() {
   CastMessage output;
-  CreateAuthChallengeMessage(&output);
+  std::unique_ptr<AuthContext> context = base::MakeUnique<AuthContext>("");
+  CreateAuthChallengeMessage(&output, context.get());
   return output;
 }
 
@@ -207,7 +208,8 @@ class TestCastSocket : public CastSocketImpl {
                        base::TimeDelta::FromMilliseconds(timeout_ms),
                        false,
                        logger,
-                       device_capabilities),
+                       device_capabilities,
+                       base::MakeUnique<AuthContext>("")),
         capturing_net_log_(capturing_net_log),
         ip_(ip_endpoint),
         extract_cert_result_(true),