predictors: Collect page load metrics for ResourcePrefetchPredictor.

chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.h

Index: chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.h
diff --git a/chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.h b/chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..cb00c68cb5b0c8afec1348cb04ef081df1fa5f3b
--- /dev/null
+++ b/chrome/browser/page_load_metrics/observers/resource_prefetch_predictor_page_load_metrics_observer.h
@@ -0,0 +1,62 @@
+// 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_RESOURCE_PREFETCH_PREDICTOR_PAGE_LOAD_METRICS_OBSERVER_H_
+#define CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_RESOURCE_PREFETCH_PREDICTOR_PAGE_LOAD_METRICS_OBSERVER_H_
+
+#include "chrome/browser/page_load_metrics/page_load_metrics_observer.h"
+
+namespace content {
+class WebContents;
+}
+
+namespace predictors {
+class ResourcePrefetchPredictor;
+}
+
+namespace internal {
+
+extern const char kHistogramResourcePrefetchPredictorFirstContentfulPaint[];
+extern const char kHistogramResourcePrefetchPredictorFirstMeaningfulPaint[];
+
+}  // namespace internal
+
+// Observer responsible for recording page load metrics relevant to
+// ResourcePrefetchPredictor.
+class ResourcePrefetchPredictorPageLoadMetricsObserver
+    : public page_load_metrics::PageLoadMetricsObserver {
+ public:
+  // Returns a ResourcePrefetchPredictorPageLoadMetricsObserver, or nullptr if
+  // it is not needed.
+  static std::unique_ptr<ResourcePrefetchPredictorPageLoadMetricsObserver>
+  CreateIfNeeded(content::WebContents* web_contents);
+
+  // Public for testing. Normally one should use CreateIfNeeded. Predictor must
+  // outlive this observer.
+  explicit ResourcePrefetchPredictorPageLoadMetricsObserver(
+      predictors::ResourcePrefetchPredictor* predictor);
+
+  ~ResourcePrefetchPredictorPageLoadMetricsObserver() override;
+
+  // page_load_metrics::PageLoadMetricsObserver:
+  ObservePolicy OnStart(content::NavigationHandle* navigation_handle,
+                        const GURL& currently_commited_url,
+                        bool started_in_foreground) override;
+  ObservePolicy OnHidden(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+  void OnFirstContentfulPaint(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+  void OnFirstMeaningfulPaint(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+
+ private:
+  predictors::ResourcePrefetchPredictor* predictor_;

[Charlie Harrison, 2017/01/13 18:56:05]

Can you document the lifetime of predictor_ and why it will outlive this class?

[Benoit L, 2017/01/16 14:04:53]

It is tied to BrowserContext, so this should be fine, right?

[Charlie Harrison, 2017/01/17 14:41:16]

Yes sounds good.

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

Acknowledged.

+
+  DISALLOW_COPY_AND_ASSIGN(ResourcePrefetchPredictorPageLoadMetricsObserver);
+};
+
+#endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_RESOURCE_PREFETCH_PREDICTOR_PAGE_LOAD_METRICS_OBSERVER_H_