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

tools/perf/perf_tools/histogram_measurement.py

+# Copyright (c) 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 perf_tools import histogram as histogram_module
+
+BROWSER_HISTOGRAM = 'browser_histogram'
+RENDERER_HISTOGRAM = 'renderer_histogram'
+
+class HistogramMeasurement(object):
+  def __init__(self, histogram, histogram_type):
+    self.name = histogram['name']
+    self.units = histogram['units']
+    self.histogram_type = histogram_type
+    self._start_values = dict()
+
+  def Start(self, page, tab):
+    """Get the starting value for the histogram. This value will then be
+    subtracted from the actual measurement."""
+    data = self._GetHistogramFromDomAutomation(tab)
+    if data:
+      self._start_values[page.url + self.name] = data
+
+  def GetValue(self, page, tab, results):
+    data = self._GetHistogramFromDomAutomation(tab)
+    if not data:
+      return
+    new_histogram = histogram_module.SubtractHistogram(
+        data, self._start_values[page.url + self.name])
+    results.Add(self.name.replace('.', '_'), self.units,
+                new_histogram, data_type='histogram')
+
+  @property
+  def histogram_function(self):
+    if self.histogram_type == BROWSER_HISTOGRAM:
+      return 'getBrowserHistogram'
+    return 'getHistogram'
+
+  def _GetHistogramFromDomAutomation(self, tab):
+    js = ('window.domAutomationController.%s ? '
+          'window.domAutomationController.%s("%s") : ""' %
+          (self.histogram_function, self.histogram_function, self.name))
+    return tab.EvaluateJavaScript(js)