Don't use gtest-parallel when running webrtc_perf_tests.

When we run webrtc_perf_tests with gtest-parallel, each test is run
individually, and this results in the file with the perf results being
overwritten each time.

To avoid this, we won't use gtest-parallel when running webrtc_perf_tests,
so we will simply run the binary directly.

TBR=phoglund@chromium.org

Bug: chromium:755660
Change-Id: I24db36e512fcf604a3de2adf4d0b4325b2c3d1ae
Reviewed-on: https://webrtc-review.googlesource.com/49340
Reviewed-by: Edward Lemur <ehmaldonado@webrtc.org>
Reviewed-by: Henrik Lundin <henrik.lundin@webrtc.org>
Commit-Queue: Edward Lemur <ehmaldonado@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21982}

tools_webrtc/gtest-parallel-wrapper.py

@@ -107,11 +107,6 @@ def _ParseArgs():
   parser.add_argument('--store-test-artifacts', action='store_true',
                       default=False)
 
-  # Used to store results of perf tests. See
-  # https://chromium.googlesource.com/external/github.com/catapult-project/catapult/+/HEAD/dashboard/docs/data-format.md
-  parser.add_argument('--isolated-script-test-perf-output', type=str,
-                      default=None)
-
   # No-sandbox is a Chromium-specific flag, ignore it.
   # TODO(oprypin): Remove (bugs.webrtc.org/8115)
   parser.add_argument('--no-sandbox', action='store_true', default=False)
@@ -145,13 +140,6 @@ def _ParseArgs():
         test_artifacts_dir,
     ]
 
-  # The corresponding flag in WebRTC is called 'chartjson_result_file'.
-  if options.isolated_script_test_perf_output:
-    executable_args += [
-        '--chartjson_result_file',
-        options.isolated_script_test_perf_output,
-    ]
-
   # GTEST_SHARD_INDEX and GTEST_TOTAL_SHARDS must be removed from the
   # environment. Otherwise it will be picked up by the binary, causing a bug
   # where only tests in the first shard are executed.