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

net/http/http_response_info.h

Index: net/http/http_response_info.h
diff --git a/net/http/http_response_info.h b/net/http/http_response_info.h
index 2dce1a1de07c9577c835cfcb8b2f2ca7bbf3e5c9..dee91d7f97a4f26d818f44a8baa6c867119dd25d 100644
--- a/net/http/http_response_info.h
+++ b/net/http/http_response_info.h
@@ -34,13 +34,14 @@ class NET_EXPORT HttpResponseInfo {
   // the cache, please make sure not to delete or reorder values.
   enum ConnectionInfo {
     CONNECTION_INFO_UNKNOWN = 0,
-    CONNECTION_INFO_HTTP1 = 1,
+    CONNECTION_INFO_HTTP1 = 1,  // HTTP/1.0 or HTTP/1.1.

[Bence, 2016/06/30 21:20:11]

Since you are touching this part of the code anyway, I think it might be
worthwhile to split this further into separate HTTP/1.0 and HTTP/1.1 values.

[mmenke, 2016/06/30 22:18:07]

Done.  They're similar enough to each other, that I wasn't sure it was worth the
effort, but it doesn't hurt.  Did turn up a case where we're now randomly
returning one of the three.

     CONNECTION_INFO_DEPRECATED_SPDY2 = 2,
     CONNECTION_INFO_SPDY3 = 3,
     CONNECTION_INFO_HTTP2 = 4,  // HTTP/2.
     CONNECTION_INFO_QUIC1_SPDY3 = 5,
     CONNECTION_INFO_HTTP2_14 = 6,  // HTTP/2 draft-14.
     CONNECTION_INFO_HTTP2_15 = 7,  // HTTP/2 draft-15.
+    CONNECTION_INFO_HTTP0_9 = 8,
     NUM_OF_CONNECTION_INFOS,
   };