Pass isolate output dir to gtest-parallel-wrapper.py

This makes it possible to archive all test execution logs on swarming jobs.

R=kjellander@webrtc.org
BUG=webrtc:7086
NOTRY=True

Review-Url: https://codereview.webrtc.org/2686563002
Cr-Commit-Position: refs/heads/master@{#16574}
diff --git a/tools-webrtc/mb/mb_unittest.py b/tools-webrtc/mb/mb_unittest.py
index 3f9a6c9..f5c5bc2 100755
--- a/tools-webrtc/mb/mb_unittest.py
+++ b/tools-webrtc/mb/mb_unittest.py
@@ -504,6 +504,7 @@
     self.assertEqual(command, [
         '../../testing/xvfb.py',
         '../../third_party/gtest-parallel/gtest-parallel-wrapper.py',
+        '--output_dir=${ISOLATED_OUTDIR}/test_logs',
         './base_unittests',
         '--',
         '--asan=0',
@@ -548,6 +549,7 @@
     self.assertEqual(command, [
         '../../testing/test_env.py',
         '../../third_party/gtest-parallel/gtest-parallel-wrapper.py',
+        '--output_dir=${ISOLATED_OUTDIR}\\test_logs',
         r'.\unittests.exe',
         '--',
         '--asan=0',
@@ -588,6 +590,7 @@
     self.assertEqual(command, [
         '../../testing/test_env.py',
         '../../third_party/gtest-parallel/gtest-parallel-wrapper.py',
+        '--output_dir=${ISOLATED_OUTDIR}/test_logs',
         './base_unittests',
         '--',
         '--asan=0',