Allow multiple devices on bisects hosts

scripts/slave/recipe_modules/auto_bisect/local_bisect.py

Index: scripts/slave/recipe_modules/auto_bisect/local_bisect.py
diff --git a/scripts/slave/recipe_modules/auto_bisect/local_bisect.py b/scripts/slave/recipe_modules/auto_bisect/local_bisect.py
index c5fb2cc8d93d65c0d111a9420be62228f68ddc0e..713c4a1c96da57add25cbf2fbe287972563c8297 100644
--- a/scripts/slave/recipe_modules/auto_bisect/local_bisect.py
+++ b/scripts/slave/recipe_modules/auto_bisect/local_bisect.py
@@ -8,25 +8,38 @@ import json
 
 
 def perform_bisect(api, **flags):  # pragma: no cover
-  bisect_config = api.m.properties.get('bisect_config')
-  assert isinstance(bisect_config, collections.Mapping)
-  bisector = api.create_bisector(bisect_config, **flags)
-  with api.m.step.nest('Gathering reference values'):
-    _gather_reference_range(api, bisector)
-  if (not bisector.failed and bisector.check_improvement_direction() and
-      bisector.check_initial_confidence()):
-    if bisector.check_reach_adjacent_revision(bisector.good_rev):
-      # Only show this step if bisect has reached adjacent revisions.
-      with api.m.step.nest(str('Check bisect finished on revision ' +
-                               bisector.good_rev.revision_string())):
-        if bisector.check_bisect_finished(bisector.good_rev):
-          bisector.bisect_over = True
-    if not bisector.bisect_over:
-      _bisect_main_loop(bisector)
-  else:
-    bisector.bisect_over = True
-  bisector.print_result_debug_info()
-  bisector.post_result(halt_on_failure=True)
+  try:
+      bisect_config = api.m.properties.get('bisect_config')
+      assert isinstance(bisect_config, collections.Mapping)
+      bisector = api.create_bisector(bisect_config, **flags)
+      with api.m.step.nest('Gathering reference values'):
+        _gather_reference_range(api, bisector)
+      if (not bisector.failed and bisector.check_improvement_direction() and
+          bisector.check_initial_confidence()):
+        if bisector.check_reach_adjacent_revision(bisector.good_rev):
+          # Only show this step if bisect has reached adjacent revisions.
+          with api.m.step.nest(str('Check bisect finished on revision ' +
+                                   bisector.good_rev.revision_string())):
+            if bisector.check_bisect_finished(bisector.good_rev):
+              bisector.bisect_over = True
+        if not bisector.bisect_over:
+          _bisect_main_loop(bisector)
+      else:
+        bisector.bisect_over = True
+      bisector.print_result_debug_info()
+      bisector.post_result(halt_on_failure=True)
+  except api.m.step.StepFailure:

[RobertoCN, 2016/06/07 22:00:39]

Eventually we'd want to make this more specific that just StepFailure. We need
to determine if the failure was due to a device going offline.
I think as a first attempt, this should work anyway.

[Ziqi Xiong, 2016/06/22 17:38:21]

Done.

+      if api.m.chromium.c.TARGET_PLATFORM == 'android':
+        api.m.chromium_android.device_status_check()
+        available_devices = api.m.chromium_android.devices()
+        if available_devices:
+          serial_number = available_devices[0]

[RobertoCN, 2016/06/07 22:00:39]

Since we do not know for a fact that the StepFailure was due to a device going
offline, we might need to check that we are not retrying with the same devices
over and over again. Maybe we could keep a running list of devices already
tested and stop when all those have been tried?

[Ziqi Xiong, 2016/06/22 17:38:21]

Done.

+          api.m.chromium_android.test_device = serial_number
+          perform_bisect(api,**flags)
+        else:
+          raise
+      else:
+        raise
 
 
 def _gather_reference_range(api, bisector):  # pragma: no cover