Fix leak of sequenced worker pool in unit tests when service_ is replaced.

net/ssl/server_bound_cert_service_unittest.cc

Index: net/ssl/server_bound_cert_service_unittest.cc
diff --git a/net/ssl/server_bound_cert_service_unittest.cc b/net/ssl/server_bound_cert_service_unittest.cc
index 0063f496036854c4c3a1ae2be4cbc1dea394ae66..d7b8553b5ac1470dbbe50f905432d066d51f2f4f 100644
--- a/net/ssl/server_bound_cert_service_unittest.cc
+++ b/net/ssl/server_bound_cert_service_unittest.cc
@@ -105,7 +105,13 @@ MockServerBoundCertStoreWithAsyncGet::CallGetServerBoundCertCallbackWithResult(
     const std::string& cert) {
   if (err == OK)
     cert_count_ = 1;
-  callback_.Run(err, server_identifier_, expiration_time, private_key, cert);
+  base::MessageLoop::current()->PostTask(FROM_HERE,
+                                         base::Bind(callback_,
+                                                    err,
+                                                    server_identifier_,
+                                                    expiration_time,
+                                                    private_key,
+                                                    cert));
 }
 
 TEST_F(ServerBoundCertServiceTest, GetDomainForHost) {