Cleanup test server instance after running each a test in gtest test runner

build/android/pylib/chrome_test_server_spawner.py

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """A "Test Server Spawner" that handles killing/stopping per-test test servers.
 
 It's used to accept requests from the device to spawn and kill instances of the
 chrome test server on the host.
 """
 
@@ skipping 379 matching lines @@
     self.server.adb = adb
     self.server.tool = tool
     self.server.test_server_instance = None
     self.server.build_type = build_type
 
   def _Listen(self):
     logging.info('Starting test server spawner')
     self.server.serve_forever()
 
   def Start(self):
+    """Starts the test server spawner."""
     listener_thread = threading.Thread(target=self._Listen)
     listener_thread.setDaemon(True)
     listener_thread.start()
     time.sleep(1)
 
   def Stop(self):
+    """Stops the test server spawner.
+
+    Also cleans the server state.
+    """
+    self.CleanupState()
+    self.server.shutdown()
+
+  def CleanupState(self):
+    """Cleans up the spawning server state.
+
+    This should be called if the test server spawner is reused,
+    to avoid sharing the test server instance.
+    """
     if self.server.test_server_instance:
       self.server.test_server_instance.Stop()
-    self.server.shutdown()
+      self.server.test_server_instance = None