Regress the metric reported by dummy_benchmark.stable_benchmark_1 by 20%

tools/perf/benchmarks/dummy_benchmark.py

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 """Dummy benchmarks for the bisect FYI integration tests.
 
 The number they produce aren't meant to represent any actual performance
 data of the browser. For more information about these dummy benchmarks,
 see: https://goo.gl/WvZiiW
 """
 
@@ skipping 25 matching lines @@
 
 
 class _DummyBenchmark(perf_benchmark.PerfBenchmark):
   page_set = dummy_story_set.DummyStorySet
 
 
 class DummyBenchmarkOne(_DummyBenchmark):
   """A low noise benchmark with mean=100 & std=1."""
 
   def CreatePageTest(self, options):
-    return _DummyTest(140, 1)
+    return _DummyTest(168, 1)
 
   @classmethod
   def Name(cls):
     return 'dummy_benchmark.stable_benchmark_1'
 
 
 class DummyBenchmarkTwo(_DummyBenchmark):
   """A noisy benchmark with mean=50 & std=20."""
 
   def CreatePageTest(self, options):
     return _DummyTest(50, 20)
 
   @classmethod
   def Name(cls):
     return 'dummy_benchmark.noisy_benchmark_1'