Add PageLoad.* metrics for Offline Previews

chrome/browser/page_load_metrics/observers/previews_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/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 kHistogramOfflinePreviewsPrefix[] =
+    "PageLoad.Clients.Previews.OfflinePages.";
+const char kHistogramDOMContentLoadedEventFiredSuffix[] =
+    "DocumentTiming.NavigationToDOMContentLoadedEventFired";
+const char kHistogramFirstLayoutSuffix[] =
+    "DocumentTiming.NavigationToFirstLayout";
+const char kHistogramLoadEventFiredSuffix[] =
+    "DocumentTiming.NavigationToLoadEventFired";
+const char kHistogramFirstContentfulPaintSuffix[] =
+    "PaintTiming.NavigationToFirstContentfulPaint";
+const char kHistogramFirstImagePaintSuffix[] =
+    "PaintTiming.NavigationToFirstImagePaint";
+const char kHistogramFirstPaintSuffix[] = "PaintTiming.NavigationToFirstPaint";
+const char kHistogramFirstTextPaintSuffix[] =
+    "PaintTiming.NavigationToFirstTextPaint";
+const char kHistogramParseStartSuffix[] = "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(

[tbansal1, 2016/08/18 22:04:53]

Would it be more readable if the boolean condition was reversed?
if(!a || !b) return;

// do something.

[RyanSturm, 2016/08/19 19:10:38]

Done.

+                                 timing.dom_content_loaded_event_start, info)) {
+    PAGE_LOAD_HISTOGRAM(
+        std::string(internal::kHistogramOfflinePreviewsPrefix)
+            .append(internal::kHistogramDOMContentLoadedEventFiredSuffix),
+        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(

[tbansal1, 2016/08/18 22:04:53]

This condition is same as everywhere else. Can it be factored out to something
like:
bool ShouldRecordTimingsMetrics() const {}

[RyanSturm, 2016/08/19 19:10:38]

It doesn't really shorten much. It would need to take three arguments (or 2 if
it was class method instead of non-class). So it's shortening a (bool &&
method(a,b)) to (method(a,b,bool)).

+                                 timing.dom_content_loaded_event_start, info)) {
+    PAGE_LOAD_HISTOGRAM(std::string(internal::kHistogramOfflinePreviewsPrefix)
+                            .append(internal::kHistogramLoadEventFiredSuffix),
+                        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)) {
+    PAGE_LOAD_HISTOGRAM(std::string(internal::kHistogramOfflinePreviewsPrefix)
+                            .append(internal::kHistogramFirstLayoutSuffix),
+                        timing.first_layout.value());
+  }
+}
+
+void PreviewsPageLoadMetricsObserver::OnFirstPaint(
+    const page_load_metrics::PageLoadTiming& timing,
+    const page_load_metrics::PageLoadExtraInfo& info) {
+  if (is_offline_preview_ && WasStartedInForegroundOptionalEventInForeground(
+                                 timing.dom_content_loaded_event_start, info)) {
+    PAGE_LOAD_HISTOGRAM(std::string(internal::kHistogramOfflinePreviewsPrefix)
+                            .append(internal::kHistogramFirstPaintSuffix),
+                        timing.first_paint.value());
+  }
+}
+
+void PreviewsPageLoadMetricsObserver::OnFirstTextPaint(
+    const page_load_metrics::PageLoadTiming& timing,
+    const page_load_metrics::PageLoadExtraInfo& info) {
+  if (is_offline_preview_ && WasStartedInForegroundOptionalEventInForeground(
+                                 timing.dom_content_loaded_event_start, info)) {
+    PAGE_LOAD_HISTOGRAM(std::string(internal::kHistogramOfflinePreviewsPrefix)
+                            .append(internal::kHistogramFirstTextPaintSuffix),
+                        timing.first_text_paint.value());
+  }
+}
+
+void PreviewsPageLoadMetricsObserver::OnFirstImagePaint(
+    const page_load_metrics::PageLoadTiming& timing,
+    const page_load_metrics::PageLoadExtraInfo& info) {
+  if (is_offline_preview_ && WasStartedInForegroundOptionalEventInForeground(
+                                 timing.dom_content_loaded_event_start, info)) {
+    PAGE_LOAD_HISTOGRAM(std::string(internal::kHistogramOfflinePreviewsPrefix)
+                            .append(internal::kHistogramFirstImagePaintSuffix),
+                        timing.first_image_paint.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)) {
+    PAGE_LOAD_HISTOGRAM(
+        std::string(internal::kHistogramOfflinePreviewsPrefix)
+            .append(internal::kHistogramFirstContentfulPaintSuffix),
+        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)) {
+    PAGE_LOAD_HISTOGRAM(std::string(internal::kHistogramOfflinePreviewsPrefix)
+                            .append(internal::kHistogramParseStartSuffix),
+                        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_preview();
+#else
+  return false;
+#endif  // BUILDFLAG(ANDROID_JAVA_UI)
+}
+
+}  // namespace previews