Convert first contentful paint logging to the new UKM client API

chrome/browser/page_load_metrics/observers/ukm_page_load_metrics_observer.h

 // 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_UKM_PAGE_LOAD_METRICS_OBSERVER_H_
 #define CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_UKM_PAGE_LOAD_METRICS_OBSERVER_H_
 
 #include "base/macros.h"
 #include "chrome/browser/page_load_metrics/page_load_metrics_observer.h"
+#include "components/ukm/ukm_entry_builder.h"
+#include "content/public/browser/global_request_id.h"
+
+namespace internal {
+
+// Name constants are exposed here so they can be referenced from tests.
+extern const char kUkmPageLoadEventName[];
+extern const char kUkmFirstContentfulPaintName[];
+
+}  // namespace internal
 
 // If URL-Keyed-Metrics (UKM) is enabled in the system, this is used to
 // populate it with top-level page-load metrics.
 class UkmPageLoadMetricsObserver
     : public page_load_metrics::PageLoadMetricsObserver {
  public:
   // Returns a UkmPageLoadMetricsObserver, or nullptr if it is not needed.
   static std::unique_ptr<page_load_metrics::PageLoadMetricsObserver>
   CreateIfNeeded();
 
   UkmPageLoadMetricsObserver();
+  ~UkmPageLoadMetricsObserver() override;
 
   // page_load_metrics::PageLoadMetricsObserver implementation:
   ObservePolicy OnStart(content::NavigationHandle* navigation_handle,
                         const GURL& currently_committed_url,
                         bool started_in_foreground) override;
 
   ObservePolicy FlushMetricsOnAppEnterBackground(
       const page_load_metrics::PageLoadTiming& timing,
       const page_load_metrics::PageLoadExtraInfo& info) override;
 
   ObservePolicy OnHidden(
       const page_load_metrics::PageLoadTiming& timing,
       const page_load_metrics::PageLoadExtraInfo& info) override;
 
+  void OnFailedProvisionalLoad(
+      const page_load_metrics::FailedProvisionalLoadInfo& failed_load_info,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+
   void OnComplete(const page_load_metrics::PageLoadTiming& timing,
                   const page_load_metrics::PageLoadExtraInfo& info) override;
 
  private:
-  void SendMetricsToUkm(const page_load_metrics::PageLoadTiming& timing,
-                        const page_load_metrics::PageLoadExtraInfo& info);
+  void AddTimingMetrics(const page_load_metrics::PageLoadTiming& timing);
+  void AddPageLoadExtraInfoMetrics(
+      const page_load_metrics::PageLoadExtraInfo& info,
+      base::TimeTicks app_background_time);
+
+  const content::GlobalRequestID global_request_id_;
+  std::unique_ptr<ukm::UkmEntryBuilder> builder_;

[Zhen Wang, 2017/03/01 19:18:00]

Builder will only add UkmEntry to UkmService when it is destructed. I remember
the observer's life ends when another navigation in the same frame commits. I am
not sure if you want to wait that long. Is that desired?

 
   DISALLOW_COPY_AND_ASSIGN(UkmPageLoadMetricsObserver);
 };
 
 #endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_UKM_PAGE_LOAD_METRICS_OBSERVER_H_