Allow multiple devices on bisects hosts

scripts/slave/recipe_modules/bisect_tester/perf_test.py

Index: scripts/slave/recipe_modules/bisect_tester/perf_test.py
diff --git a/scripts/slave/recipe_modules/bisect_tester/perf_test.py b/scripts/slave/recipe_modules/bisect_tester/perf_test.py
index 057e8a152aaf8a24f12059e0a802cff38b1a93cb..e362f76ca076828a4167275f7f9ef89d4b851f52 100644
--- a/scripts/slave/recipe_modules/bisect_tester/perf_test.py
+++ b/scripts/slave/recipe_modules/bisect_tester/perf_test.py
@@ -91,6 +91,12 @@ def run_perf_test(api, test_config, **kwargs):
   use_chartjson = bool('chartjson' in command)
   is_telemetry = _is_telemetry_command(command)
   start_time = time.time()
+
+  if api.m.chromium.c.TARGET_PLATFORM == 'android':
+    device_serial_number = api.m.chromium_android.test_device;
+    if device_serial_number:
+      command += '--device ' + device_serial_number

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

I think this flag can only be appended to telemetry commands, might be worth it
to check for it (use the _is_telemetry boolean from line 92)

+
   for i in range(repeat_cnt):
     elapsed_minutes = (time.time() - start_time) / 60.0
     # A limit of 0 means 'no timeout set'.