Telemetry / Memory benchmark fix: Separate histograms for different tests.

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 histogram_measurement
 from telemetry import multi_page_benchmark
 
 MEMORY_HISTOGRAMS = [
     {'name': 'V8.MemoryExternalFragmentationTotal', 'units': 'percent'},
     {'name': 'V8.MemoryHeapSampleTotalCommitted', 'units': 'kb'},
     {'name': 'V8.MemoryHeapSampleTotalUsed', 'units': 'kb'},
     {'name': 'Memory.RendererUsed', 'units': 'kb'}]
 
 BROWSER_MEMORY_HISTOGRAMS =  [
     {'name': 'Memory.BrowserUsed', 'units': 'kb'}]
 
 class MemoryBenchmark(multi_page_benchmark.MultiPageBenchmark):
   def __init__(self):
     super(MemoryBenchmark, self).__init__('stress_memory')
+    self.histograms = (
+        [histogram_measurement.HistogramMeasurement(h)
+         for h in MEMORY_HISTOGRAMS] +
+        [histogram_measurement.HistogramMeasurement(h, True)
+         for h in BROWSER_MEMORY_HISTOGRAMS])
+
+  def WillNavigateToPage(self, page, tab):
+    for h in self.histograms:
+      h.Start(page, tab)
 
   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:
-      self._GetHistogramFromDomAutomation(tab, 'getHistogram', histogram,
-                                          results)
-    for histogram in BROWSER_MEMORY_HISTOGRAMS:
-      self._GetHistogramFromDomAutomation(tab, 'getBrowserHistogram', histogram,
-                                          results)
-
-  def _GetHistogramFromDomAutomation(self, tab, func, histogram, results):
-    name = histogram['name']
-    js = ('window.domAutomationController.%s ? '
-          'window.domAutomationController.%s("%s") : ""' % (func, func, name))
-    data = tab.EvaluateJavaScript(js)
-    if data:
-      results.Add(name.replace('.', '_'), histogram['units'], data,
-                  data_type='histogram')
+    for h in self.histograms:
+      h.GetValue(page, tab, results)