Dump json output for webrtc tests using gtest_parallel.

This is required step in order to upload tests results to ResultDB.

Bug: b/197492097
Change-Id: Ia25e63c649361c9e09d0710bd582d9511348fc90
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/238423
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Jeremy Leconte <jleconte@google.com>
Cr-Commit-Position: refs/heads/main@{#35386}
diff --git a/tools_webrtc/gtest-parallel-wrapper.py b/tools_webrtc/gtest-parallel-wrapper.py
index 26b9afa..d4460ae 100755
--- a/tools_webrtc/gtest-parallel-wrapper.py
+++ b/tools_webrtc/gtest-parallel-wrapper.py
@@ -133,6 +133,7 @@
     # These options will be passed unchanged to gtest-parallel.
     gtest_group.AddArgument('-d', '--output_dir')
     gtest_group.AddArgument('-r', '--repeat')
+    gtest_group.AddArgument('--dump_json_test_results')
     gtest_group.AddArgument('--retry_failed')
     gtest_group.AddArgument('--gtest_color')
     gtest_group.AddArgument('--gtest_filter')
@@ -144,8 +145,8 @@
     # Syntax 'Nx' will be interpreted as N * number of cpu cores.
     gtest_group.AddArgument('-w', '--workers', type=_ParseWorkersOption)
 
-    # Needed when the test wants to store test artifacts, because it doesn't know
-    # what will be the swarming output dir.
+    # Needed when the test wants to store test artifacts, because it doesn't
+    # know what will be the swarming output dir.
     parser.add_argument('--store-test-artifacts', action='store_true')
 
     # No-sandbox is a Chromium-specific flag, ignore it.