Enable usb_mix_sel1 for stress tests.

BUG=chrome-os-partner:62245
TEST=Tested for previously failing DUT

Change-Id: I5c02bfb341f05dd1168f68bfc61c3786c3d414b6
Reviewed-on: https://chromium-review.googlesource.com/439535
Commit-Ready: Kalin Stoyanov <kalin@chromium.org>
Tested-by: Kalin Stoyanov <kalin@chromium.org>
Reviewed-by: danny chan <dchan@chromium.org>
Reviewed-by: Lawrence Hui <lhui@chromium.org>
(cherry picked from commit 8bb5f507f1e4a8e3738f64bb0664c05c19df41fd)
Reviewed-on: https://chromium-review.googlesource.com/440145
diff --git a/server/site_tests/platform_ExternalUsbPeripherals/control.stress b/server/site_tests/platform_ExternalUsbPeripherals/control.stress
index 96551fc..63e1455 100644
--- a/server/site_tests/platform_ExternalUsbPeripherals/control.stress
+++ b/server/site_tests/platform_ExternalUsbPeripherals/control.stress
@@ -45,6 +45,7 @@
 
     job.run_test("platform_ExternalUsbPeripherals", host=host,
                  disable_sysinfo=True, client_autotest="desktopui_SimpleLogin",
-                 action_sequence=action_sequence, repeat=repeat, tag="stress")
+                 action_sequence=action_sequence, repeat=repeat,
+                 stress_rack=True, tag="stress")
 
 parallel_simple(run, machines)
diff --git a/server/site_tests/platform_ExternalUsbPeripherals/control.stress2 b/server/site_tests/platform_ExternalUsbPeripherals/control.stress2
index 301cf81..64502df 100644
--- a/server/site_tests/platform_ExternalUsbPeripherals/control.stress2
+++ b/server/site_tests/platform_ExternalUsbPeripherals/control.stress2
@@ -45,6 +45,7 @@
 
     job.run_test("platform_ExternalUsbPeripherals", host=host,
                  disable_sysinfo=True, client_autotest="desktopui_SimpleLogin",
-                 action_sequence=action_sequence, repeat=repeat, tag="stress2")
+                 action_sequence=action_sequence, repeat=repeat,
+                 stress_rack=True, tag="stress2")
 
 parallel_simple(run, machines)
diff --git a/server/site_tests/platform_ExternalUsbPeripherals/control.stress3 b/server/site_tests/platform_ExternalUsbPeripherals/control.stress3
index e2242c8..a7b9afa 100644
--- a/server/site_tests/platform_ExternalUsbPeripherals/control.stress3
+++ b/server/site_tests/platform_ExternalUsbPeripherals/control.stress3
@@ -45,6 +45,7 @@
 
     job.run_test("platform_ExternalUsbPeripherals", host=host,
                  disable_sysinfo=True, client_autotest="desktopui_SimpleLogin",
-                 action_sequence=action_sequence, repeat=repeat, tag="stress3")
+                 action_sequence=action_sequence, repeat=repeat,
+                 stress_rack=True, tag="stress3")
 
 parallel_simple(run, machines)
diff --git a/server/site_tests/platform_ExternalUsbPeripherals/platform_ExternalUsbPeripherals.py b/server/site_tests/platform_ExternalUsbPeripherals/platform_ExternalUsbPeripherals.py
index 160aa36..6f34607 100644
--- a/server/site_tests/platform_ExternalUsbPeripherals/platform_ExternalUsbPeripherals.py
+++ b/server/site_tests/platform_ExternalUsbPeripherals/platform_ExternalUsbPeripherals.py
@@ -269,7 +269,8 @@
 
 
     def run_once(self, host, client_autotest, action_sequence, repeat,
-                 usb_list=None, usb_checks=None, crash_check=False):
+                 usb_list=None, usb_checks=None,
+                 crash_check=False, stress_rack=False):
         self.client_autotest = client_autotest
         self.host = host
         self.autotest_client = autotest.Autotest(self.host)
@@ -283,7 +284,10 @@
         self.action_step = None
 
         self.host.servo.switch_usbkey('dut')
-        self.host.servo.set('usb_mux_sel1', 'servo_sees_usbkey')
+        if (stress_rack):
+            self.host.servo.set('usb_mux_sel1', 'dut_sees_usbkey')
+        else:
+            self.host.servo.set('usb_mux_sel1', 'servo_sees_usbkey')
         self.host.servo.set('usb_mux_sel3', 'dut_sees_usbkey')
         time.sleep(_WAIT_DELAY)