Adding previews information to PLM UKM

chrome/browser/page_load_metrics/page_load_tracker.cc

 // Copyright 2016 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 "chrome/browser/page_load_metrics/page_load_tracker.h"
 
 #include <algorithm>
 #include <ostream>
 #include <string>
 #include <utility>
@@ skipping 621 matching lines @@
   }
 }
 
 void PageLoadTracker::OnSubframeMetadataChanged() {
   PageLoadExtraInfo extra_info(ComputePageLoadExtraInfo());
   for (const auto& observer : observers_) {
     observer->OnLoadingBehaviorObserved(extra_info);
   }
 }
 
+void PageLoadTracker::BroadcastEventToObservers(const void* const event_key) {
+  for (const auto& observer : observers_) {
+    observer->OnEventOccurred(event_key);
+  }
+}
+
 }  // namespace page_load_metrics