[NoStatePrefetch] Add UMA histogram to count prefetch requests

chrome/browser/prerender/prerender_manager.cc

Index: chrome/browser/prerender/prerender_manager.cc
diff --git a/chrome/browser/prerender/prerender_manager.cc b/chrome/browser/prerender/prerender_manager.cc
index 17d875d45db8ab44ac7af2890c1a9dfa0cbfc712..7864ceeb2bdf4931a8c0e37dcc5c2b7b64170500 100644
--- a/chrome/browser/prerender/prerender_manager.cc
+++ b/chrome/browser/prerender/prerender_manager.cc
@@ -551,6 +551,12 @@ void PrerenderManager::RecordPerceivedPageLoadTime(
   }
 }
 
+void PrerenderManager::RecordResourcePrefetch(Origin origin,
+                                              bool is_main_resource,
+                                              bool is_no_store) {
+  histograms_->RecordResourcePrefetch(origin, is_main_resource, is_no_store);
+}
+
 // static
 PrerenderManager::PrerenderManagerMode PrerenderManager::GetMode() {
   return mode_;