Rewrite broken Facebook test case in top_7_stress

tools/perf/benchmarks/memory.py

 # Copyright 2013 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 measurements import memory
 import page_sets
 from telemetry import benchmark
 
 
 @benchmark.Enabled('android')
 class MemoryMobile(benchmark.Benchmark):
   test = memory.Memory
   page_set = page_sets.MobileMemoryPageSet
 
 
-@benchmark.Disabled
 class MemoryTop7Stress(benchmark.Benchmark):
   test = memory.Memory
   page_set = page_sets.Top7StressPageSet
 
 
 @benchmark.Disabled
 class Reload2012Q3(benchmark.Benchmark):
   tag = 'reload'
   test = memory.Memory
   page_set = page_sets.Top2012Q3StressPageSet
 
 
 @benchmark.Disabled  # crbug.com/371153
 class MemoryToughDomMemoryCases(benchmark.Benchmark):
   test = memory.Memory
   page_set = page_sets.ToughDomMemoryCasesPageSet
 
 
 @benchmark.Disabled('chromeos', 'linux', 'mac', 'win')
 @benchmark.Enabled('has tabs')
 class TypicalMobileSites(benchmark.Benchmark):
   """Long memory test."""
   test = memory.Memory
   page_set = page_sets.TypicalMobileSitesPageSet
   options = {'pageset_repeat': 15}