Add ReloadPageLoadMetricsObserver to have a metrics variant for reloads

chrome/browser/page_load_metrics/observers/reload_page_load_metrics_observer.cc

+// 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.
+
+#include "chrome/browser/page_load_metrics/observers/reload_page_load_metrics_observer.h"
+
+#include "chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h"
+#include "components/page_load_metrics/browser/page_load_metrics_util.h"
+#include "ui/base/page_transition_types.h"
+
+namespace chrome {
+
+namespace {
+
+const char kHistogramFirstContentfulPaintReload[] =
+    "PageLoad.Clients.Reload.PaintTiming.NavigationToFirstContentfulPaint";
+const char kHistogramFirstContentfulPaintReloadByGesture[] =
+    "PageLoad.Clients.Reload.PaintTiming.NavigationToFirstContentfulPaint."
+    "UserGesture";
+
+}  // namespace
+
+ReloadPageLoadMetricsObserver::ReloadPageLoadMetricsObserver()
+    : page_transition_was_reload_(false), initiated_by_user_gesture_(false) {}
+
+void ReloadPageLoadMetricsObserver::OnCommit(
+    content::NavigationHandle* navigation_handle) {
+  page_transition_was_reload_ = ui::PageTransitionCoreTypeIs(
+      navigation_handle->GetPageTransition(), ui::PAGE_TRANSITION_RELOAD);
+  initiated_by_user_gesture_ = navigation_handle->HasUserGesture();
+}
+
+void ReloadPageLoadMetricsObserver::OnFirstContentfulPaint(
+    const page_load_metrics::PageLoadTiming& timing,
+    const page_load_metrics::PageLoadExtraInfo& extra_info) {
+  if (!page_transition_was_reload_ ||
+      !WasStartedInForegroundEventInForeground(timing.first_contentful_paint,
+                                               extra_info)) {
+    return;
+  }
+
+  PAGE_LOAD_HISTOGRAM(kHistogramFirstContentfulPaintReload,
+                      timing.first_contentful_paint);
+  if (initiated_by_user_gesture_) {
+    PAGE_LOAD_HISTOGRAM(kHistogramFirstContentfulPaintReloadByGesture,
+                        timing.first_contentful_paint);
+  }
+}
+
+}  // namespace chrome