HttpServerProperties - Added a histogram to track the AlternateProtocolServers

net/http/http_server_properties_manager.cc

Index: net/http/http_server_properties_manager.cc
diff --git a/net/http/http_server_properties_manager.cc b/net/http/http_server_properties_manager.cc
index b8e3e0c5fc3078710a75ea0b573a60d6bbbf547e..4ccb0ef0a073f22ab4025ecea1ce5750be952cac 100644
--- a/net/http/http_server_properties_manager.cc
+++ b/net/http/http_server_properties_manager.cc
@@ -884,6 +884,8 @@ void HttpServerPropertiesManager::UpdatePrefsFromCacheOnNetworkThread(
       new AlternativeServiceMap(kMaxAlternateProtocolHostsToPersist);
   const AlternativeServiceMap& map =
       http_server_properties_impl_->alternative_service_map();
+  UMA_HISTOGRAM_COUNTS("Net.CountOfAlternateProtocolServers.Memory",
+                       map.size());
   count = 0;
   typedef std::map<std::string, bool> CanonicalHostPersistedMap;
   CanonicalHostPersistedMap persisted_map;