mac: Expose keychain access frequency to Telemetry.

tools/perf/measurements/memory_pressure.py

Index: tools/perf/measurements/memory_pressure.py
diff --git a/tools/perf/measurements/memory_pressure.py b/tools/perf/measurements/memory_pressure.py
index 182cac529fe563ad2c4d3cf1b3137bfb71317b78..e9b0d1d1358e04b3805d849cd8a3f9c048f76496 100644
--- a/tools/perf/measurements/memory_pressure.py
+++ b/tools/perf/measurements/memory_pressure.py
@@ -10,11 +10,11 @@ the entire test rather than each single page.
 
 import logging
 
+from measurements import PageTestMeasurement
 from telemetry.value import histogram_util
-from telemetry.page import page_test
 
 
-class MemoryPressure(page_test.PageTest):
+class MemoryPressure(PageTestMeasurement):
   def __init__(self, *args, **kwargs):
     super(MemoryPressure, self).__init__(*args, **kwargs)
     # _first_tab is used to access histograms
@@ -23,6 +23,7 @@ class MemoryPressure(page_test.PageTest):
 
   # Allow histogram collection
   def CustomizeBrowserOptions(self, options):
+    super(MemoryPressure, self).CustomizeBrowserOptions(options)
     histogram_util.CustomizeBrowserOptions(options)
 
   # Open a new tab at each page
@@ -38,6 +39,8 @@ class MemoryPressure(page_test.PageTest):
     return (discard_count, kill_count)
 
   def ValidateAndMeasurePage(self, page, tab, results):
+    super(MemoryPressure, self).ValidateAndMeasurePage(page, tab, results)
+
     # After navigating to each page, check if it triggered tab discards or
     # kills.
     (discard_count, kill_count) = self.GetTabsHistogramCounts(tab)