Android Perf tests: obtain the list of tests from the test runner.

build/android/pylib/perf/test_runner.py

Index: build/android/pylib/perf/test_runner.py
diff --git a/build/android/pylib/perf/test_runner.py b/build/android/pylib/perf/test_runner.py
index 1d0a25cedbbda3a662651aa2f7f01d6059854f4e..9eeda20b349336f6431eab65ab5d3b06edc77cef 100644
--- a/build/android/pylib/perf/test_runner.py
+++ b/build/android/pylib/perf/test_runner.py
@@ -57,6 +57,7 @@ option:
 
 import collections
 import datetime
+import json
 import logging
 import os
 import pickle
@@ -71,6 +72,19 @@ from pylib.base import base_test_result
 from pylib.base import base_test_runner
 
 
+def OutputJsonList(json_input, json_output):
+  with file(json_input, 'r') as i:
+    all_steps = json.load(i)
+  # TODO(bulach): remove once it rolls downstream, crbug.com/378862.
+  if isinstance(all_steps, list):
+    step_names = [t[0] for t in all_steps]
+  else:
+    step_names = all_steps['steps'].keys()
+  with file(json_output, 'w') as o:
+    o.write(json.dumps(step_names))
+  return 0
+
+
 def PrintTestOutput(test_name):
   """Helper method to print the output of previously executed test_name.