Notify page load metrics when the app enters the background.

chrome/browser/metrics/page_load_metrics_provider.h

Index: chrome/browser/metrics/page_load_metrics_provider.h
diff --git a/chrome/browser/metrics/page_load_metrics_provider.h b/chrome/browser/metrics/page_load_metrics_provider.h
new file mode 100644
index 0000000000000000000000000000000000000000..00c6eff19db1220fd44c25e5f38f1ea28f8382c6
--- /dev/null
+++ b/chrome/browser/metrics/page_load_metrics_provider.h
@@ -0,0 +1,23 @@
+// Copyright 2016 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_METRICS_PAGE_LOAD_METRICS_PROVIDER_H_
+#define CHROME_BROWSER_METRICS_PAGE_LOAD_METRICS_PROVIDER_H_
+
+#include "base/macros.h"
+#include "components/metrics/metrics_provider.h"
+
+class PageLoadMetricsProvider : public metrics::MetricsProvider {
+ public:
+  PageLoadMetricsProvider();
+  ~PageLoadMetricsProvider() override;
+
+  // metrics:MetricsProvider:
+  void OnAppEnterBackground() override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(PageLoadMetricsProvider);
+};
+
+#endif  // CHROME_BROWSER_METRICS_PAGE_LOAD_METRICS_PROVIDER_H_