Adding TabRestore PLM UMA

chrome/browser/page_load_metrics/observers/tab_restore_page_load_metrics_observer.h

Index: chrome/browser/page_load_metrics/observers/tab_restore_page_load_metrics_observer.h
diff --git a/chrome/browser/page_load_metrics/observers/tab_restore_page_load_metrics_observer.h b/chrome/browser/page_load_metrics/observers/tab_restore_page_load_metrics_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..316500c236faf93326a33cb1e6dde3b42e5e033a
--- /dev/null
+++ b/chrome/browser/page_load_metrics/observers/tab_restore_page_load_metrics_observer.h
@@ -0,0 +1,61 @@
+// Copyright 2017 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_TAB_RESTORE_PAGE_LOAD_METRICS_OBSERVER_H_
+#define CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_TAB_RESTORE_PAGE_LOAD_METRICS_OBSERVER_H_
+
+#include <stdint.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 core page load metrics relevant to
+// restored tabs.
+class TabRestorePageLoadMetricsObserver
+    : public page_load_metrics::PageLoadMetricsObserver {
+ public:
+  TabRestorePageLoadMetricsObserver();
+  ~TabRestorePageLoadMetricsObserver() override;
+
+  // page_load_metrics::PageLoadMetricsObserver:
+  void OnComplete(const page_load_metrics::PageLoadTiming& timing,
+                  const page_load_metrics::PageLoadExtraInfo& info) override;
+  page_load_metrics::PageLoadMetricsObserver::ObservePolicy OnStart(
+      content::NavigationHandle* navigation_handle,
+      const GURL& currently_committed_url,
+      bool started_in_foreground) override;
+  void OnLoadedResource(
+      const page_load_metrics::ExtraRequestInfo& extra_request_info) override;
+  page_load_metrics::PageLoadMetricsObserver::ObservePolicy
+  FlushMetricsOnAppEnterBackground(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& info) override;
+
+ protected:
+  // Whether the navigation handle is a tab restore.
+  // Overridden in testing.
+  virtual bool IsTabRestore(content::NavigationHandle* navigation_handle);
+
+ private:
+  // Records histograms for byte information.
+  void RecordByteHistograms();
+
+  // The number of body (not header) prefilter bytes consumed by requests for
+  // the page.
+  int64_t cache_bytes_;
+  int64_t network_bytes_;
+
+  DISALLOW_COPY_AND_ASSIGN(TabRestorePageLoadMetricsObserver);
+};
+
+#endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_TAB_RESTORE_PAGE_LOAD_METRICS_OBSERVER_H_