Enable loading.mobile benchmark on Android except reference and webview

tools/perf/benchmarks/loading.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.
 
 from core import perf_benchmark
 import page_sets
 
 from benchmarks import page_cycler_v2
 from telemetry import benchmark
 from telemetry.page import cache_temperature
 
 
-@benchmark.Disabled('all')  # crbug.com/654215
+@benchmark.Enabled('android')
 class LoadingMobile(perf_benchmark.PerfBenchmark):
   """ A benchmark measuring loading performance of mobile sites. """
 
   options = {'pageset_repeat': 2}
 
   def CreateTimelineBasedMeasurementOptions(self):
     return page_cycler_v2.TimelineBasedMeasurementOptionsForLoadingMetric()
 
   @classmethod
+  def ShouldDisable(cls, possible_browser):
+    # crbug.com/619254
+    if possible_browser.browser_type == 'reference':
+      return True
+
+    # crbug.com/651188
+    if possible_browser.browser_type == 'android-webview':
+      return True
+
+    return False
+
+  @classmethod
   def Name(cls):
     return 'loading.mobile'
 
   def CreateStorySet(self, options):
     return page_sets.LoadingMobileStorySet(cache_temperatures=[
           cache_temperature.ANY])