Add PageLoad.* metrics for Offline Previews

chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer.cc

Index: chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer.cc
diff --git a/chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer.cc b/chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..cb8ed69d6c2e08b9693e965bf0221f4c42762732
--- /dev/null
+++ b/chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer.cc
@@ -0,0 +1,123 @@
+// 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/previews_page_load_metrics_observer.h"
+
+#include <string>
+
+#include "base/optional.h"
+#include "base/time/time.h"
+#include "chrome/browser/page_load_metrics/page_load_metrics_util.h"
+#include "chrome/common/features.h"
+#include "chrome/common/page_load_metrics/page_load_timing.h"
+#include "content/public/browser/navigation_handle.h"
+#include "content/public/browser/web_contents.h"
+
+#if BUILDFLAG(ANDROID_JAVA_UI)
+#include "chrome/browser/android/offline_pages/offline_page_tab_helper.h"
+#endif  // BUILDFLAG(ANDROID_JAVA_UI)
+
+namespace previews {
+
+namespace internal {
+
+const char kHistogramDOMContentLoadedEventFired[] =
+    "PageLoad.Clients.Previews.OfflinePages.DocumentTiming."
+    "NavigationToDOMContentLoadedEventFired";
+const char kHistogramFirstLayout[] =
+    "PageLoad.Clients.Previews.OfflinePages.DocumentTiming."
+    "NavigationToFirstLayout";
+const char kHistogramLoadEventFired[] =
+    "PageLoad.Clients.Previews.OfflinePages.DocumentTiming."
+    "NavigationToLoadEventFired";
+const char kHistogramFirstContentfulPaint[] =
+    "PageLoad.Clients.Previews.OfflinePages.PaintTiming."
+    "NavigationToFirstContentfulPaint";
+const char kHistogramParseStart[] =
+    "PageLoad.Clients.Previews.OfflinePages.ParseTiming.NavigationToParseStart";
+
+}  // namespace internal
+
+PreviewsPageLoadMetricsObserver::PreviewsPageLoadMetricsObserver()
+    : is_offline_preview_(false) {}
+
+PreviewsPageLoadMetricsObserver::~PreviewsPageLoadMetricsObserver() {}
+
+void PreviewsPageLoadMetricsObserver::OnCommit(
+    content::NavigationHandle* navigation_handle) {
+  is_offline_preview_ = IsOfflinePreview(navigation_handle->GetWebContents());
+}
+
+void PreviewsPageLoadMetricsObserver::OnDomContentLoadedEventStart(
+    const page_load_metrics::PageLoadTiming& timing,
+    const page_load_metrics::PageLoadExtraInfo& info) {
+  if (!is_offline_preview_ ||
+      !WasStartedInForegroundOptionalEventInForeground(
+          timing.dom_content_loaded_event_start, info)) {
+    return;
+  }
+  PAGE_LOAD_HISTOGRAM(internal::kHistogramDOMContentLoadedEventFired,
+                      timing.dom_content_loaded_event_start.value());
+}
+
+void PreviewsPageLoadMetricsObserver::OnLoadEventStart(
+    const page_load_metrics::PageLoadTiming& timing,
+    const page_load_metrics::PageLoadExtraInfo& info) {
+  if (!is_offline_preview_ ||
+      !WasStartedInForegroundOptionalEventInForeground(
+          timing.dom_content_loaded_event_start, info)) {
+    return;
+  }
+  PAGE_LOAD_HISTOGRAM(internal::kHistogramLoadEventFired,
+                      timing.load_event_start.value());
+}
+
+void PreviewsPageLoadMetricsObserver::OnFirstLayout(
+    const page_load_metrics::PageLoadTiming& timing,
+    const page_load_metrics::PageLoadExtraInfo& info) {
+  if (!is_offline_preview_ ||
+      !WasStartedInForegroundOptionalEventInForeground(
+          timing.dom_content_loaded_event_start, info)) {
+    return;
+  }
+  PAGE_LOAD_HISTOGRAM(internal::kHistogramFirstLayout,
+                      timing.first_layout.value());
+}
+
+void PreviewsPageLoadMetricsObserver::OnFirstContentfulPaint(
+    const page_load_metrics::PageLoadTiming& timing,
+    const page_load_metrics::PageLoadExtraInfo& info) {
+  if (!is_offline_preview_ ||
+      !WasStartedInForegroundOptionalEventInForeground(
+          timing.dom_content_loaded_event_start, info)) {
+    return;
+  }
+  PAGE_LOAD_HISTOGRAM(internal::kHistogramFirstContentfulPaint,
+                      timing.first_contentful_paint.value());
+}
+
+void PreviewsPageLoadMetricsObserver::OnParseStart(
+    const page_load_metrics::PageLoadTiming& timing,
+    const page_load_metrics::PageLoadExtraInfo& info) {
+  if (!is_offline_preview_ ||
+      !WasStartedInForegroundOptionalEventInForeground(
+          timing.dom_content_loaded_event_start, info)) {
+    return;
+  }
+  PAGE_LOAD_HISTOGRAM(internal::kHistogramParseStart,
+                      timing.parse_start.value());
+}
+
+bool PreviewsPageLoadMetricsObserver::IsOfflinePreview(
+    content::WebContents* web_contents) const {
+#if BUILDFLAG(ANDROID_JAVA_UI)
+  offline_pages::OfflinePageTabHelper* tab_helper =
+      offline_pages::OfflinePageTabHelper::FromWebContents(web_contents);
+  return tab_helper && tab_helper->is_offline_preview();
+#else
+  return false;
+#endif  // BUILDFLAG(ANDROID_JAVA_UI)
+}
+
+}  // namespace previews