Histogram the amount of time spent on HTTP(S) page loads

chrome/browser/page_load_metrics/observers/https_engagement_page_load_metrics_observer.h

Index: chrome/browser/page_load_metrics/observers/https_engagement_page_load_metrics_observer.h
diff --git a/chrome/browser/page_load_metrics/observers/https_engagement_page_load_metrics_observer.h b/chrome/browser/page_load_metrics/observers/https_engagement_page_load_metrics_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..58552f51648eec7de3f590e2708106a14eee01a2
--- /dev/null
+++ b/chrome/browser/page_load_metrics/observers/https_engagement_page_load_metrics_observer.h
@@ -0,0 +1,41 @@
+// 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_PAGE_LOAD_METRICS_OBSERVERS_HTTPS_ENGAGEMENT_PAGE_LOAD_METRICS_OBSERVER_H_
+#define CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_HTTPS_ENGAGEMENT_PAGE_LOAD_METRICS_OBSERVER_H_
+
+#include "base/macros.h"
+#include "base/time/time.h"
+#include "components/page_load_metrics/browser/page_load_metrics_observer.h"
+#include "url/gurl.h"
+
+namespace internal {
+extern const char kHttpsEngagementHistogram[];
+extern const char kHttpEngagementHistogram[];
+}  // namespace internal
+
+class HttpsEngagementPageLoadMetricsObserver
+    : public page_load_metrics::PageLoadMetricsObserver {
+ public:
+  HttpsEngagementPageLoadMetricsObserver();
+
+  // page_load_metrics::PageLoadMetricsObserver:
+  void OnStart(content::NavigationHandle* navigation_handle,
+               const GURL& currently_committed_url,
+               bool started_in_foreground) override;
+  void OnHidden() override;
+  void OnShown() override;
+  void OnComplete(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+
+ private:
+  bool currently_in_foreground_;
+  base::TimeDelta foreground_time_;
+  base::TimeTicks last_time_shown_;
+
+  DISALLOW_COPY_AND_ASSIGN(HttpsEngagementPageLoadMetricsObserver);
+};
+
+#endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_HTTPS_ENGAGEMENT_PAGE_LOAD_METRICS_OBSERVER_H_