Avoid Adding Field Trial Flags If Flag is Set.

This CL is a follow up CL of CL: 1174721. So we don't add field trial flag when
the new compatibility mode flag is set.

Bug: chromium:866881
Cq-Include-Trybots: master.tryserver.chromium.perf:obbs_fyi
Change-Id: I5dae5a130445b9c61ad40cb13744a6272947424b
Reviewed-on: https://chromium-review.googlesource.com/1175127Reviewed-by: Ned Nguyen <nednguyen@google.com>
Reviewed-by: Juan Antonio Navarro Pérez <perezju@chromium.org>
Commit-Queue: Leonard Ge <wangge@google.com>
Cr-Commit-Position: refs/heads/master@{#584057}

tools/perf/core/perf_benchmark.py

@@ -90,7 +90,8 @@ class PerfBenchmark(benchmark.Benchmark):
     #
     # The same logic applies to the ad filtering ruleset, which could be in a
     # binary format that an older build does not expect.
-    if options.browser_type != 'reference' and not options.compatibility_mode:
+    if options.browser_type != 'reference' and ('no-field-trials' not in
+        options.compatibility_mode):
       variations = self._GetVariationsBrowserArgs(options.finder_options)
       options.AppendExtraBrowserArgs(variations)
 

tools/perf/core/perf_benchmark_unittest.py

@@ -94,7 +94,7 @@ class PerfBenchmarkTest(unittest.TestCase):
     benchmark = perf_benchmark.PerfBenchmark()
     options = options_for_unittests.GetCopy()
     options.chrome_root = self._output_dir
-    options.browser_options.compatibility_mode = True
+    options.browser_options.compatibility_mode = ['no-field-trials']
     benchmark.CustomizeBrowserOptions(options.browser_options)
 
     for arg in expected_args: