Adding previews information to PLM UKM

chrome/browser/page_load_metrics/page_load_metrics_initialize.cc

Index: chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
diff --git a/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc b/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
index ce05d706ecad1940e87d4ac1c8d9f1545e771679..d6885a95cb474cda0ded0957631d3fa75f2057e6 100644
--- a/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
+++ b/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
@@ -33,6 +33,7 @@
 #include "chrome/browser/page_load_metrics/observers/omnibox_suggestion_used_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/prerender_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer.h"
+#include "chrome/browser/page_load_metrics/observers/previews_ukm_observer.h"
 #include "chrome/browser/page_load_metrics/observers/protocol_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/service_worker_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/subresource_filter_metrics_observer.h"
@@ -97,6 +98,7 @@ void PageLoadMetricsEmbedder::RegisterObservers(
         base::MakeUnique<MultiTabLoadingPageLoadMetricsObserver>());
     tracker->AddObserver(
         base::MakeUnique<previews::PreviewsPageLoadMetricsObserver>());
+    tracker->AddObserver(base::MakeUnique<previews::PreviewsUKMObserver>());
     tracker->AddObserver(
         base::MakeUnique<ServiceWorkerPageLoadMetricsObserver>());
     tracker->AddObserver(base::MakeUnique<SubresourceFilterMetricsObserver>());