Adding previews information to PLM UKM

services/metrics/public/cpp/ukm_recorder.h

Index: services/metrics/public/cpp/ukm_recorder.h
diff --git a/services/metrics/public/cpp/ukm_recorder.h b/services/metrics/public/cpp/ukm_recorder.h
index fcefa5bc01212130cefe73f4d6ac2b948609b84b..c40bf43783a123b1cf4880d49d7d8f93ea95cc06 100644
--- a/services/metrics/public/cpp/ukm_recorder.h
+++ b/services/metrics/public/cpp/ukm_recorder.h
@@ -50,6 +50,10 @@ class PasswordManagerMetricsRecorder;
 class PasswordFormMetricsRecorder;
 }  // namespace password_manager
 
+namespace previews {
+class PreviewsUKMObserver;
+}
+
 namespace ukm {
 
 class UkmEntryBuilder;
@@ -100,6 +104,7 @@ class METRICS_EXPORT UkmRecorder {
   friend content::RenderWidgetHostLatencyTracker;
   friend password_manager::PasswordManagerMetricsRecorder;
   friend password_manager::PasswordFormMetricsRecorder;
+  friend previews::PreviewsUKMObserver;
   friend resource_coordinator::CoordinationUnitManager;
   FRIEND_TEST_ALL_PREFIXES(UkmServiceTest, AddEntryWithEmptyMetrics);
   FRIEND_TEST_ALL_PREFIXES(UkmServiceTest, EntryBuilderAndSerialization);
@@ -127,4 +132,4 @@ class METRICS_EXPORT UkmRecorder {
 
 }  // namespace ukm
 
-#endif  // SERVICES_METRICS_PUBLIC_CPP_UKM_RECORDER_H_
+#endif  // COMPONENTS_UKM_PUBLIC_UKM_RECORDER_H_