xvfb: Fix race condition in unit test

Bug: 1114251
Change-Id: I59f4fbe6cf6cc96895eb3e2d9bc8b8578009a5c7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2342256
Auto-Submit: Gary Tong <[email protected]>
Reviewed-by: Dirk Pranke <[email protected]>
Reviewed-by: Ilia Samsonov <[email protected]>
Commit-Queue: Gary Tong <[email protected]>
Cr-Commit-Position: refs/heads/master@{#796596}
diff --git a/testing/xvfb_unittest.py b/testing/xvfb_unittest.py
index 4aab40baa..b84196f4 100755
--- a/testing/xvfb_unittest.py
+++ b/testing/xvfb_unittest.py
@@ -94,13 +94,13 @@
 
   def test_send_sigint(self):
     proc = launch_process(['--sleep'])
-    send_signal(proc, signal.SIGINT)
+    send_signal(proc, signal.SIGINT, 1)
     sig = read_subprocess_message(proc, 'Signal :')
     self.assertEqual(sig, str(signal.SIGINT))
 
   def test_send_sigterm(self):
     proc = launch_process(['--sleep'])
-    send_signal(proc, signal.SIGTERM)
+    send_signal(proc, signal.SIGTERM, 1)
     sig = read_subprocess_message(proc, 'Signal :')
     self.assertEqual(sig, str(signal.SIGTERM))