Construct a field trial to see if HIGH or MEDIUM memory model "works better"...

chrome/browser/render_widget_host_view_win.cc

Index: chrome/browser/render_widget_host_view_win.cc
===================================================================
--- chrome/browser/render_widget_host_view_win.cc	(revision 3603)
+++ chrome/browser/render_widget_host_view_win.cc	(working copy)
@@ -11,6 +11,7 @@
 #include "base/win_util.h"
 #include "chrome/browser/browser_accessibility.h"
 #include "chrome/browser/browser_accessibility_manager.h"
+#include "chrome/browser/browser_trial.h"
 #include "chrome/browser/render_process_host.h"
 // TODO(beng): (Cleanup) we should not need to include this file... see comment
 //             in |DidBecomeSelected|.
@@ -433,7 +434,21 @@
     }
     if (!whiteout_start_time_.is_null()) {
       TimeDelta whiteout_duration = TimeTicks::Now() - whiteout_start_time_;
-      UMA_HISTOGRAM_TIMES(L"MPArch.RWHH_WhiteoutDuration", whiteout_duration);
+
+      // If field trial is active, report results in special histogram.
+      static scoped_refptr<FieldTrial> trial(
+          FieldTrialList::Find(BrowserTrial::kMemoryModelFieldTrial));
+      if (trial.get()) {
+        if (trial->boolean_value())
+          UMA_HISTOGRAM_TIMES(L"MPArch.RWHH_WhiteoutDuration_trial_high_memory",
+                              whiteout_duration);
+        else
+          UMA_HISTOGRAM_TIMES(L"MPArch.RWHH_WhiteoutDuration_trial_med_memory",
+                              whiteout_duration);
+      } else {
+        UMA_HISTOGRAM_TIMES(L"MPArch.RWHH_WhiteoutDuration", whiteout_duration);
+      }
+
       // Reset the start time to 0 so that we start recording again the next
       // time the backing store is NULL...
       whiteout_start_time_ = TimeTicks();