Use exit command to stop web page replay server.

tools/telemetry/telemetry/core/wpr_server.py

Index: tools/telemetry/telemetry/core/wpr_server.py
diff --git a/tools/telemetry/telemetry/core/wpr_server.py b/tools/telemetry/telemetry/core/wpr_server.py
index d36874e1605705e9237b5c73ab9de24cfa8a512c..9ac8662765d0bc721070402131eb270e429dd37b 100644
--- a/tools/telemetry/telemetry/core/wpr_server.py
+++ b/tools/telemetry/telemetry/core/wpr_server.py
@@ -9,13 +9,17 @@ util.AddDirToPythonPath(
     util.GetChromiumSrcDir(), 'chrome', 'test', 'functional')
 import webpagereplay  # pylint: disable=F0401
 
+
 def GetChromeFlags(replay_host, http_port, https_port):
   return webpagereplay.GetChromeFlags(replay_host, http_port, https_port)
 
-class _WebPageReplayServer(webpagereplay.ReplayServer): # pylint: disable=W0232
+
+class _WebPageReplayServer(webpagereplay.ReplayServer):  # pylint: disable=W0232
   def _AddDefaultReplayOptions(self):
-    """Override. Because '--no-dns_forwarding' is added by default in parent
-       while webdriver-based backends need dns forwarding."""
+    """Override to avoid adding 'no-dns_forwarding' by default.
+
+      Webdriver-based backends need dns forwarding.
+    """
     self.replay_options += [
         '--port', str(self._http_port),
         '--ssl_port', str(self._https_port),
@@ -23,6 +27,7 @@ class _WebPageReplayServer(webpagereplay.ReplayServer): # pylint: disable=W0232
         '--log_level', 'warning'
         ]
 
+
 class ReplayServer(object):
   def __init__(self, browser_backend, path, is_record_mode, is_append_mode,
                make_javascript_deterministic, webpagereplay_host,