Add PageLoad metrics for multi-tab loading cases

chrome/browser/page_load_metrics/observers/multi_tab_loading_page_load_metrics_observer.h

Index: chrome/browser/page_load_metrics/observers/multi_tab_loading_page_load_metrics_observer.h
diff --git a/chrome/browser/page_load_metrics/observers/multi_tab_loading_page_load_metrics_observer.h b/chrome/browser/page_load_metrics/observers/multi_tab_loading_page_load_metrics_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..5753f20d8eaad4250cdd304f931944c7929cc92c
--- /dev/null
+++ b/chrome/browser/page_load_metrics/observers/multi_tab_loading_page_load_metrics_observer.h
@@ -0,0 +1,63 @@
+// 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_MULTI_TAB_LOADING_PAGE_LOAD_METRICS_OBSERVER_H_
+#define CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_MULTI_TAB_LOADING_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 internal {
+
+// Exposed for tests.
+extern const char kHistogramMultiTabLoadingFirstContentfulPaint[];
+extern const char kHistogramMultiTabLoadingForegroundToFirstContentfulPaint[];
+extern const char kHistogramMultiTabLoadingFirstMeaningfulPaint[];
+extern const char kHistogramMultiTabLoadingForegroundToFirstMeaningfulPaint[];
+extern const char kHistogramMultiTabLoadingDomContentLoaded[];
+extern const char kBackgroundHistogramMultiTabLoadingDomContentLoaded[];
+extern const char kHistogramMultiTabLoadingLoad[];
+extern const char kBackgroundHistogramMultiTabLoadingLoad[];
+
+}  // namespace internal
+
+// Observer responsible for recording core page load metrics while there are
+// other loading tabs.
+class MultiTabLoadingPageLoadMetricsObserver
+    : public page_load_metrics::PageLoadMetricsObserver {
+ public:
+  MultiTabLoadingPageLoadMetricsObserver();
+  ~MultiTabLoadingPageLoadMetricsObserver() override;
+
+  // page_load_metrics::PageLoadMetricsObserver:
+  page_load_metrics::PageLoadMetricsObserver::ObservePolicy OnStart(
+      content::NavigationHandle* navigation_handle,
+      const GURL& currently_committed_url,
+      bool started_in_foreground) override;
+  void OnFirstContentfulPaintInPage(
+      const page_load_metrics::mojom::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+  void OnFirstMeaningfulPaintInMainFrameDocument(
+      const page_load_metrics::mojom::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& info) override;
+  void OnDomContentLoadedEventStart(
+      const page_load_metrics::mojom::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& info) override;
+  void OnLoadEventStart(
+      const page_load_metrics::mojom::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& info) override;
+
+ protected:
+  // Overridden in testing.
+  virtual bool IsAnyTabLoading(content::NavigationHandle* navigation_handle);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MultiTabLoadingPageLoadMetricsObserver);
+};
+
+#endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_MULTI_TAB_LOADING_PAGE_LOAD_METRICS_OBSERVER_H_