Revert of [Android] Disable system_health.common_mobile on nexus 7 devices.

tools/perf/benchmarks/system_health.py

 # Copyright 2016 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.
 
 import re
 
 from benchmarks import page_cycler_v2
 
 from core import perf_benchmark
 
@@ skipping 59 matching lines @@
   """Mobile Chrome Energy System Health Benchmark."""
   PLATFORM = 'mobile'
 
   @classmethod
   def ShouldDisable(cls, possible_browser):
     # http://crbug.com/612144
     if (possible_browser.browser_type == 'reference' and
         possible_browser.platform.GetDeviceTypeName() == 'Nexus 5X'):
       return True
 
-    # http://crbug.com/667470
-    if 'Nexus 7' in possible_browser.platform.GetDeviceTypeName():
-      return True
-
     return possible_browser.platform.GetDeviceTypeName() == 'Desktop'
 
 
 class _MemorySystemHealthBenchmark(perf_benchmark.PerfBenchmark):
   """Chrome Memory System Health Benchmark.
 
   This test suite is run separately from the common one due to the high overhead
   of memory tracing.
 
   https://goo.gl/Jek2NL.
@@ skipping 95 matching lines @@
   and load a blank page with multiprocess enabled.
   """
 
   def SetExtraBrowserOptions(self, options):
     options.AppendExtraBrowserArgs(
         ['--webview-sandboxed-renderer'])
 
   @classmethod
   def Name(cls):
     return 'system_health.webview_startup_multiprocess'