Fix swarming tests not running in parallel

tools-webrtc/gtest-parallel-wrapper.py

Index: tools-webrtc/gtest-parallel-wrapper.py
diff --git a/tools-webrtc/gtest-parallel-wrapper.py b/tools-webrtc/gtest-parallel-wrapper.py
index 0a31f63a729ae59530990c6943d2035b0e1347fa..cb83f1907d676cfa259d0162913352d329d20537 100755
--- a/tools-webrtc/gtest-parallel-wrapper.py
+++ b/tools-webrtc/gtest-parallel-wrapper.py
@@ -59,6 +59,11 @@ def main():
 
   parser = argparse.ArgumentParser()
   parser.add_argument('--isolated-script-test-output', type=str, default=None)
+
+  # TODO(ehmaldonado): Implement this flag instead of just "eating" it.
+  parser.add_argument('--isolated-script-test-chartjson-output', type=str,
+                      default=None)
+
   parser.add_argument('--output_dir', type=str, default=None)
   parser.add_argument('--timeout', type=int, default=None)