Add test for showing confirmation dialog for unsecure signin

net/test/embedded_test_server/embedded_test_server.h

Index: net/test/embedded_test_server/embedded_test_server.h
diff --git a/net/test/embedded_test_server/embedded_test_server.h b/net/test/embedded_test_server/embedded_test_server.h
index a490f25775d48cf3c82adef580c8d8ec86c67ca9..82303e51c21f1ea461f448386cde7f38167dc4b5 100644
--- a/net/test/embedded_test_server/embedded_test_server.h
+++ b/net/test/embedded_test_server/embedded_test_server.h
@@ -38,6 +38,11 @@ class HttpListenSocket : public TCPListenSocket {
   virtual ~HttpListenSocket();
   virtual void Listen();
 
+  // Listen on the current IO thread. If the IO thread has changed since this
+  // object is constructed, call |ListenOnIOThread| to make sure it listens on
+  // the right thread. Otherwise must call |Listen| instead.
+  void ListenOnIOThread();
+
  private:
   friend class EmbeddedTestServer;