fix test broken issue when using --use-emulator

build/android/pylib/single_test_runner.py

 # Copyright (c) 2012 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.
 
 import glob
 import logging
 import os
 import sys
 
 from base_test_runner import BaseTestRunner
@@ skipping 293 matching lines @@
         self._gtest_filter = ('-' + ':'.join(self.GetDisabledTests()) + ':' +
                              ':'.join(['*.' + x + '*' for x in
                                      self.test_package.GetDisabledPrefixes()]))
       self.RunTestsWithFilter()
     return self.test_results
 
   def SetUp(self):
     """Sets up necessary test enviroment for the test suite."""
     super(SingleTestRunner, self).SetUp()
     self.adb.ClearApplicationState(constants.CHROME_PACKAGE)
+    # Sometimes adb server lost connection to the emulator, which will break the
+    # test, so restart the adb server before the test.
+    self.adb.Adb().RestartAdbServer()
     if self.test_package.performance_test:
       self.adb.SetupPerformanceTest()
     if self.dump_debug_info:
       self.dump_debug_info.StartRecordingLog(True)
     self.StripAndCopyFiles()
     self.LaunchHelperToolsForTestSuite()
     self.tool.SetupEnvironment()
 
   def TearDown(self):
     """Cleans up the test enviroment for the test suite."""
     self.tool.CleanUpEnvironment()
     if self.test_package.cleanup_test_files:
       self.adb.RemovePushedFiles()
     if self.dump_debug_info:
       self.dump_debug_info.StopRecordingLog()
     if self.test_package.performance_test:
       self.adb.TearDownPerformanceTest()
     super(SingleTestRunner, self).TearDown()