Log operator code histogram on new metric log

chrome/browser/chrome_browser_main.h

Index: chrome/browser/chrome_browser_main.h
diff --git a/chrome/browser/chrome_browser_main.h b/chrome/browser/chrome_browser_main.h
index a856a2b7f392bb7f850a375bfef0c86ccc06ea68..8d473e6e1f42ed1c37dfe5ededcae2b839c76197 100644
--- a/chrome/browser/chrome_browser_main.h
+++ b/chrome/browser/chrome_browser_main.h
@@ -20,6 +20,7 @@
 
 class BrowserProcessImpl;
 class ChromeBrowserMainExtraParts;
+class ChromeBrowserMetricsServiceObserver;
 class FieldTrialSynchronizer;
 class MetricsService;
 class PrefService;
@@ -148,6 +149,9 @@ class ChromeBrowserMainParts : public content::BrowserMainParts {
   // SetupMetricsAndFieldTrials is called.
   scoped_ptr<base::FieldTrialList> field_trial_list_;
 
+  // Observe and log histograms on new metric logs.
+  scoped_ptr<ChromeBrowserMetricsServiceObserver> metrics_service_observer_;
+
   ChromeBrowserFieldTrials browser_field_trials_;
 
   // Vector of additional ChromeBrowserMainExtraParts.