Adding AMP cache PageLoad.* metrics

chrome/browser/page_load_metrics/observers/amp_page_load_metrics_observer.h

+// 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_AMP_PAGE_LOAD_METRICS_OBSERVER_H_
+#define CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_AMP_PAGE_LOAD_METRICS_OBSERVER_H_
+
+#include "base/macros.h"
+#include "chrome/browser/page_load_metrics/page_load_metrics_observer.h"
+
+namespace content {
+class NavigationHandle;
+}
+
+namespace page_load_metrics {
+struct PageLoadExtraInfo;
+struct PageLoadTiming;
+}
+
+// Observer responsible for recording page load metrics relevant to page served
+// from the AMP cache. When AMP pages are served in a same page navigation, UMA
+// is not recorded; this is typical for AMP pages navigated to from google.com.
+// Navigations to AMP pages from the google search app or directly to the amp
+// cache page will be tracked. Refreshing an AMP page served from google.com
+// will be tracked.
+class AMPPageLoadMetricsObserver
+    : public page_load_metrics::PageLoadMetricsObserver {
+ public:
+  AMPPageLoadMetricsObserver();
+  ~AMPPageLoadMetricsObserver() override;
+
+  // page_load_metrics::PageLoadMetricsObserver:
+  ObservePolicy OnCommit(content::NavigationHandle* navigation_handle) override;
+  void OnDomContentLoadedEventStart(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& info) override;
+  void OnLoadEventStart(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& info) override;
+  void OnFirstLayout(const page_load_metrics::PageLoadTiming& timing,
+                     const page_load_metrics::PageLoadExtraInfo& info) override;
+  void OnFirstContentfulPaint(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& info) override;
+  void OnParseStart(const page_load_metrics::PageLoadTiming& timing,
+                    const page_load_metrics::PageLoadExtraInfo& info) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(AMPPageLoadMetricsObserver);
+};
+
+#endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_AMP_PAGE_LOAD_METRICS_OBSERVER_H_