Add additional PageLoad UKM metrics using 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"
 
 namespace internal {
 
 // Name constants are exposed here so they can be referenced from tests.
 extern const char kUkmPageLoadEventName[];
+extern const char kUkmParseStartName[];
+extern const char kUkmDomContentLoadedName[];
+extern const char kUkmLoadEventName[];
 extern const char kUkmFirstContentfulPaintName[];
+extern const char kUkmFirstMeaningfulPaintName[];
+extern const char kUkmForegroundDurationName[];
 
 }  // 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>
@@ skipping 21 matching lines @@
 
   void OnComplete(const page_load_metrics::PageLoadTiming& timing,
                   const page_load_metrics::PageLoadExtraInfo& info) override;
 
  private:
   // Records page load timing related metrics available in PageLoadTiming, such
   // as first contentful paint.
   void RecordTimingMetrics(const page_load_metrics::PageLoadTiming& timing);
 
   // Records metrics based on the PageLoadExtraInfo struct, as well as updating
-  // the URL.
+  // the URL. |app_background_time| should be set to a timestamp if the app was
+  // backgrounded, otherwise it should be set to a null TimeTicks.
   void RecordPageLoadExtraInfoMetrics(
-      const page_load_metrics::PageLoadExtraInfo& info);
+      const page_load_metrics::PageLoadExtraInfo& info,
+      base::TimeTicks app_background_time);
 
   // Unique UKM identifier for the page load we are recording metrics for.
   const int32_t source_id_;
 
   DISALLOW_COPY_AND_ASSIGN(UkmPageLoadMetricsObserver);
 };
 
 #endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_UKM_PAGE_LOAD_METRICS_OBSERVER_H_