predictors: Collect page load metrics for ResourcePrefetchPredictor.

chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.cc

Index: chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.cc
diff --git a/chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.cc b/chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..0d383adeb10375f5966d33cf62b475f3e58c0d5a
--- /dev/null
+++ b/chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.cc
@@ -0,0 +1,79 @@
+// 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.
+
+#include "chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.h"
+
+#include "base/memory/ptr_util.h"
+#include "chrome/browser/page_load_metrics/page_load_metrics_util.h"
+#include "chrome/browser/predictors/resource_prefetch_predictor.h"
+#include "chrome/browser/predictors/resource_prefetch_predictor_factory.h"
+#include "content/public/browser/web_contents.h"
+
+namespace internal {
+
+const char kHistogramResourcePrefetchPredictorFirstContentfulPaint[] =
+    "PageLoad.Clients.ResourcePrefetchPredictor.ParseTiming."
+    "NavigationToFirstContentfulPaint.Prefetchable";
+const char kHistogramResourcePrefetchPredictorFirstMeaningfulPaint[] =
+    "PageLoad.Clients.ResourcePrefetchPredictor.ParseTiming."
+    "NavigationToFirstMeaningfulPaint.Prefetchable";
+
+}  // namespace internal
+
+// static
+std::unique_ptr<ResourcePrefetchPredictorPageLoadMetricsObserver>
+ResourcePrefetchPredictorPageLoadMetricsObserver::CreateIfNeeded(
+    content::WebContents* web_contents) {
+  predictors::ResourcePrefetchPredictor* predictor =
+      predictors::ResourcePrefetchPredictorFactory::GetForProfile(
+          web_contents->GetBrowserContext());
+  if (!predictor)
+    return nullptr;

[Benoit L, 2017/01/13 17:31:56]

nice: the nullptr_t constructor if unique_ptr is not explicit, the other one is.

[alexilin, 2017/01/24 12:49:20]

Acknowledged.

+  return base::MakeUnique<ResourcePrefetchPredictorPageLoadMetricsObserver>(
+      predictor);
+}
+
+ResourcePrefetchPredictorPageLoadMetricsObserver::
+    ResourcePrefetchPredictorPageLoadMetricsObserver(
+        predictors::ResourcePrefetchPredictor* predictor)
+    : predictor_(predictor) {
+  DCHECK(predictor_);
+}
+
+ResourcePrefetchPredictorPageLoadMetricsObserver::
+    ~ResourcePrefetchPredictorPageLoadMetricsObserver() {}
+
+page_load_metrics::PageLoadMetricsObserver::ObservePolicy
+ResourcePrefetchPredictorPageLoadMetricsObserver::OnStart(
+    content::NavigationHandle* navigation_handle,
+    const GURL& currently_commited_url,
+    bool started_in_foreground) {
+  return (started_in_foreground &&
+          predictor_->IsUrlPrefetchable(navigation_handle->GetURL()))
+             ? CONTINUE_OBSERVING
+             : STOP_OBSERVING;
+}
+
+page_load_metrics::PageLoadMetricsObserver::ObservePolicy
+ResourcePrefetchPredictorPageLoadMetricsObserver::OnHidden(
+    const page_load_metrics::PageLoadTiming& timing,
+    const page_load_metrics::PageLoadExtraInfo& extra_info) {
+  return STOP_OBSERVING;
+}
+
+void ResourcePrefetchPredictorPageLoadMetricsObserver::OnFirstContentfulPaint(
+    const page_load_metrics::PageLoadTiming& timing,
+    const page_load_metrics::PageLoadExtraInfo& extra_info) {
+  PAGE_LOAD_HISTOGRAM(
+      internal::kHistogramResourcePrefetchPredictorFirstContentfulPaint,
+      timing.first_contentful_paint.value());
+}
+
+void ResourcePrefetchPredictorPageLoadMetricsObserver::OnFirstMeaningfulPaint(
+    const page_load_metrics::PageLoadTiming& timing,
+    const page_load_metrics::PageLoadExtraInfo& extra_info) {
+  PAGE_LOAD_HISTOGRAM(
+      internal::kHistogramResourcePrefetchPredictorFirstMeaningfulPaint,
+      timing.first_meaningful_paint.value());
+}