Telemetry (memory benchmark): Add histogram Memory.RendererUsed.

tools/perf/perf_tools/memory_benchmark.py

 # Copyright (c) 2012 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 telemetry import multi_page_benchmark
 
 MEMORY_HISTOGRAMS = [
     {'name': 'V8.MemoryExternalFragmentationTotal', 'units': 'percent'},
     {'name': 'V8.MemoryHeapSampleTotalCommitted', 'units': 'kb'},
-    {'name': 'V8.MemoryHeapSampleTotalUsed', 'units': 'kb'}]
+    {'name': 'V8.MemoryHeapSampleTotalUsed', 'units': 'kb'},
+    {'name': 'Memory.RendererUsed', 'units': 'kb'}]
 
 class MemoryBenchmark(multi_page_benchmark.MultiPageBenchmark):
   def __init__(self):
     super(MemoryBenchmark, self).__init__('stress_memory')
 
   def CustomizeBrowserOptions(self, options):
     options.AppendExtraBrowserArg('--dom-automation')
     # For a hard-coded set of Google pages (such as GMail), we produce custom
     # memory histograms (V8.Something_gmail) instead of the generic histograms
     # (V8.Something), if we detect that a renderer is only rendering this page
     # and no other pages. For this test, we need to disable histogram
     # customizing, so that we get the same generic histograms produced for all
     # pages.
     options.AppendExtraBrowserArg('--disable-histogram-customizer')
+    options.AppendExtraBrowserArg('--memory-metrics')
 
   def CanRunForPage(self, page):
     return hasattr(page, 'stress_memory')
 
   def MeasurePage(self, page, tab, results):
     for histogram in MEMORY_HISTOGRAMS:
       name = histogram['name']
       data = tab.runtime.Evaluate(
           'window.domAutomationController.getHistogram ? '
           'window.domAutomationController.getHistogram("%s") : ""' % name)
       if data:
         results.Add(name.replace('.', '_'), histogram['units'], data,
                     data_type='histogram')