Use new Background method in memory perf test.

tools/perf/benchmarks/memory.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.
 
 import re
 
 from core import perf_benchmark
 
 from telemetry import benchmark
 from telemetry.timeline import chrome_trace_category_filter
@@ skipping 54 matching lines @@
 
   @classmethod
   def Name(cls):
     return 'memory.top_10_mobile'
 
   @classmethod
   def ShouldTearDownStateAfterEachStoryRun(cls):
     return False
 
   @classmethod
-  def ShouldDisable(cls, possible_browser):
-    # TODO(crbug.com/586148): Benchmark should not depend on DeskClock app.
-    return not possible_browser.platform.CanLaunchApplication(
-        'com.google.android.deskclock')
-
-  @classmethod
   def ValueCanBeAddedPredicate(cls, value, is_first_result):
     # TODO(crbug.com/610962): Remove this stopgap when the perf dashboard
     # is able to cope with the data load generated by TBMv2 metrics.
     return not _IGNORED_STATS_RE.search(value.name)
 
 
 class MemoryBenchmarkTop10MobileStress(MemoryBenchmarkTop10Mobile):
   """Run top 10 mobile page set without closing/restarting the browser.
 
   This benchmark is intended to stress-test the browser, catching memory leaks
@@ skipping 157 matching lines @@
   of long running idle Gmail page """
   page_set = page_sets.LongRunningIdleGmailBackgroundPageSet
 
   @classmethod
   def Name(cls):
     return 'memory.long_running_idle_gmail_background_tbmv2'
 
   @classmethod
   def ShouldDisable(cls, possible_browser):  # http://crbug.com/616530
     return cls.IsSvelte(possible_browser)