[Cronet] Continue UrlRequest with NULL certificate if Client cert is requested.

components/cronet/android/cronet_url_request_adapter.cc

Index: components/cronet/android/cronet_url_request_adapter.cc
diff --git a/components/cronet/android/cronet_url_request_adapter.cc b/components/cronet/android/cronet_url_request_adapter.cc
index 9f9c524be1f626f386d5e1a43a51850698fc72eb..b541a6ec797e37c3782957ced96d1d106085d3a4 100644
--- a/components/cronet/android/cronet_url_request_adapter.cc
+++ b/components/cronet/android/cronet_url_request_adapter.cc
@@ -257,6 +257,14 @@ void CronetURLRequestAdapter::OnReceivedRedirect(
   *defer_redirect = true;
 }
 
+void CronetURLRequestAdapter::OnCertificateRequested(
+    net::URLRequest* request,
+    net::SSLCertRequestInfo* cert_request_info) {
+  DCHECK(context_->IsOnNetworkThread());
+  // Cronet does not support client certificates.
+  request->ContinueWithCertificate(nullptr, nullptr);
+}
+
 void CronetURLRequestAdapter::OnSSLCertificateError(
     net::URLRequest* request,
     const net::SSLInfo& ssl_info,