Add metric with time between background tab being foregrounded and the first paint

components/page_load_metrics/browser/page_load_metrics_util.cc

 // Copyright 2015 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 "components/page_load_metrics/browser/page_load_metrics_util.h"
 
 #include <algorithm>
 
 #include "components/page_load_metrics/browser/page_load_metrics_observer.h"
 #include "components/page_load_metrics/common/page_load_timing.h"
 
 namespace page_load_metrics {
 
-bool EventOccurredInForeground(base::TimeDelta event,
-                               const PageLoadExtraInfo& info) {
+bool WasStartedInForegroundEventInForeground(base::TimeDelta event,
+                                             const PageLoadExtraInfo& info) {
   return info.started_in_foreground && !event.is_zero() &&
          (info.first_background_time.is_zero() ||
           event < info.first_background_time);
 }
 
 }  // namespace page_load_metrics