Manual partial update from from https://crrev.com/337502

build/android/pylib/instrumentation/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.
 
 """Class for running instrumentation tests on a single device."""
 
 import logging
 import os
 import re
 import sys
@@ skipping 325 matching lines @@
     results = base_test_result.TestRunResults()
     timeout = (self._GetIndividualTestTimeoutSecs(test) *
                self._GetIndividualTestTimeoutScale(test) *
                self.tool.GetTimeoutScale())
 
     start_ms = 0
     duration_ms = 0
     try:
       self.TestSetup(test)
 
+      try:
+        self.device.GoHome()
+      except device_errors.CommandTimeoutError:
+        logging.exception('Failed to focus the launcher.')
+
       time_ms = lambda: int(time.time() * 1000)
       start_ms = time_ms()
       raw_output = self._RunTest(test, timeout)
       duration_ms = time_ms() - start_ms
 
       # Parse the test output
       result_code, result_bundle, statuses = (
           instrumentation_test_instance.ParseAmInstrumentRawOutput(raw_output))
       result = self._GenerateTestResult(
           test, result_code, result_bundle, statuses, start_ms, duration_ms)
       if local_device_instrumentation_test_run.DidPackageCrashOnDevice(
           self.test_pkg.GetPackageName(), self.device):
         result.SetType(base_test_result.ResultType.CRASH)
       results.AddResult(result)
     except device_errors.CommandTimeoutError as e:
       results.AddResult(test_result.InstrumentationTestResult(
           test, base_test_result.ResultType.TIMEOUT, start_ms, duration_ms,
           log=str(e) or 'No information'))
     except device_errors.DeviceUnreachableError as e:
       results.AddResult(test_result.InstrumentationTestResult(
           test, base_test_result.ResultType.CRASH, start_ms, duration_ms,
           log=str(e) or 'No information'))
     self.TestTeardown(test, results)
     return (results, None if results.DidRunPass() else test)