[Android] Add ability to generate test trace json for perf tests runs.

build/android/pylib/perf/perf_test_instance.py

Index: build/android/pylib/perf/perf_test_instance.py
diff --git a/build/android/pylib/perf/perf_test_instance.py b/build/android/pylib/perf/perf_test_instance.py
index fbb7962d588a9c08bfaa74f42273d374e0d7434f..3121d8d405ae45ac0b617f1e4dd78a7a3eb4cc2f 100644
--- a/build/android/pylib/perf/perf_test_instance.py
+++ b/build/android/pylib/perf/perf_test_instance.py
@@ -79,6 +79,7 @@ class PerfTestInstance(test_instance.TestInstance):
         ' '.join(args.single_step_command) if args.single_step else None)
     self._steps = args.steps
     self._test_filter = args.test_filter
+    self._trace_output = args.trace_output
     self._write_buildbot_json = args.write_buildbot_json
 
   #override
@@ -236,6 +237,10 @@ class PerfTestInstance(test_instance.TestInstance):
   def test_filter(self):
     return self._test_filter
 
+  @property
+  def trace_output(self):
+    return self._trace_output
+
 
 class PersistentDataError(base_error.BaseError):
   def __init__(self, message):