Add directory option for JUnit coverage files.

build/android/pylib/junit/test_runner.py

Index: build/android/pylib/junit/test_runner.py
diff --git a/build/android/pylib/junit/test_runner.py b/build/android/pylib/junit/test_runner.py
index 6238fe13927d3187a0718d85fb041e298c0bf658..d255eed14f5209d49f4613139fbab6f040623f45 100644
--- a/build/android/pylib/junit/test_runner.py
+++ b/build/android/pylib/junit/test_runner.py
@@ -19,6 +19,7 @@ class JavaTestRunner(object):
     self._sdk_version = args.sdk_version
     self._test_filter = args.test_filter
     self._test_suite = args.test_suite
+    self._coverage_dir = args.coverage_dir
 
   def SetUp(self):
     pass
@@ -39,6 +40,8 @@ class JavaTestRunner(object):
         command.extend(['-runner-filter', self._runner_filter])
       if self._sdk_version:
         command.extend(['-sdk-version', self._sdk_version])
+      if self._coverage_dir:
+        command.extend(['-Demma.coverage.out.file=' + self._coverage_dir])
       return_code = cmd_helper.RunCmd(command)
       results_list = json_results.ParseResultsFromJson(
           json.loads(json_file.read()))