Log operator code histogram on new metric log

chrome/browser/chrome_browser_metrics_service_observer.h

+// Copyright 2014 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.
+
+#ifndef CHROME_BROWSER_CHROME_BROWSER_METRICS_SERVICE_OBSERVER_H_
+#define CHROME_BROWSER_CHROME_BROWSER_METRICS_SERVICE_OBSERVER_H_
+
+#include "chrome/browser/metrics/metrics_service_observer.h"
+
+// ChromeBrowserMetricsServiceObserver receives notifications when the metrics
+// service creates a new metrics log.
+class ChromeBrowserMetricsServiceObserver : public MetricsServiceObserver {
+ public:
+  ChromeBrowserMetricsServiceObserver();
+  virtual ~ChromeBrowserMetricsServiceObserver();
+
+  // MetricsServiceObserver:
+  virtual void OnDidCreateMetricsLog() OVERRIDE;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ChromeBrowserMetricsServiceObserver);
+};
+
+#endif  // CHROME_BROWSER_CHROME_BROWSER_METRICS_SERVICE_OBSERVER_H_