Don't log background navigations in StaleWhileRevalidateExperiment histograms

components/page_load_metrics/browser/page_load_metrics_util.cc

Index: components/page_load_metrics/browser/page_load_metrics_util.cc
diff --git a/components/page_load_metrics/browser/page_load_metrics_util.cc b/components/page_load_metrics/browser/page_load_metrics_util.cc
index 9b641e52d0778bed7a72b0b39b2e0bb507f6cc91..c2ae703e7338f54aa1aabd61d0c20a1adb1c21b5 100644
--- a/components/page_load_metrics/browser/page_load_metrics_util.cc
+++ b/components/page_load_metrics/browser/page_load_metrics_util.cc
@@ -18,5 +18,10 @@ base::TimeDelta GetFirstContentfulPaint(const PageLoadTiming& timing) {
   return std::min(timing.first_text_paint, timing.first_image_paint);
 }
 
-}  // namespace page_load_metrics
+bool EventOccurredInForeground(const base::TimeDelta& event,
+                               const base::TimeDelta& first_background) {
+  return !event.is_zero() &&
+         (first_background.is_zero() || event < first_background);
+}
 
+}  // namespace page_load_metrics