Add metrics to track HTTP/0.9 usage for main frames and subresources

net/http/http_response_info.cc

Index: net/http/http_response_info.cc
diff --git a/net/http/http_response_info.cc b/net/http/http_response_info.cc
index b0c23e032880bc4afa0222bb70139e304466aa2f..d5e5d2c520b5781d41e3859d4dc3c95e70539565 100644
--- a/net/http/http_response_info.cc
+++ b/net/http/http_response_info.cc
@@ -436,6 +436,8 @@ std::string HttpResponseInfo::ConnectionInfoToString(
       return "h2";
     case CONNECTION_INFO_QUIC1_SPDY3:
       return "quic/1+spdy/3";
+    case CONNECTION_INFO_HTTP0_9:
+      return "http/0.9";
     case NUM_OF_CONNECTION_INFOS:
       break;
   }