Log connectivity check response error code

Bug: b/134656880 b/134444097
Test: Build and Run
Change-Id: Idf225dfcb6a8fa1cf59de207149b764b658a94fa
Signed-off-by: Edward Wang <wangedward@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1668537Reviewed-by: Sergey Volk <servolk@chromium.org>
Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#671385}

chromecast/net/connectivity_checker_impl.cc

@@ -209,7 +209,7 @@ void ConnectivityCheckerImpl::OnResponseStarted(net::URLRequest* request,
     timeout_.Cancel();
     return;
   }
-  DVLOG(1) << "Connectivity check failed: " << http_response_code;
+  LOG(ERROR) << "Connectivity check failed: " << http_response_code;
   OnUrlRequestError(ErrorType::BAD_HTTP_STATUS);
   timeout_.Cancel();
 }