Expose SPDY pushes in DevTools

net/base/load_timing_info.h

Index: net/base/load_timing_info.h
diff --git a/net/base/load_timing_info.h b/net/base/load_timing_info.h
index 8ee5a22ec14c8da3e74dc061d87d3c09f6b13053..2c938df36d7bac191e147995e64bc104896c135d 100644
--- a/net/base/load_timing_info.h
+++ b/net/base/load_timing_info.h
@@ -38,12 +38,20 @@ namespace net {
 // send_end
 // receive_headers_end
 //
-// Times represent when a request starts/stops blocking on an event, not the
-// time the events actually occurred.  In particular, in the case of preconnects
+// Times represent when a request starts/stops blocking on an event(*), not the
+// time the events actually occurred. In particular, in the case of preconnects
 // and socket reuse, no time may be spent blocking on establishing a connection.
 // In the case of SPDY, PAC scripts are only run once for each shared session,
 // so no time may be spent blocking on them.
 //
+// (*) Note 1: push_start and push_end are the exception to this, as they
+// represent the operation which is asynchronous to normal request flow and
+// hence are provided as absolute values and not converted to "blocking" time.
+//
+// (*) Note 2: Internally to the network stack, times are those of actual event
+// occurrence. URLRequest converts them to time which the network stack was
+// blocked on each state, as per resource timing specs.
+//
 // DNS and SSL times are both times for the host, not the proxy, so DNS times
 // when using proxies are null, and only requests to HTTPS hosts (Not proxies)
 // have SSL times.  One exception to this is when a proxy server itself returns
@@ -52,9 +60,6 @@ namespace net {
 // See HttpNetworkTransaction::OnHttpsProxyTunnelResponse.
 // TODO(mmenke):  Is this worth fixing?
 //
-// Note that internal to the network stack, times are when events actually
-// occurred.  URLRequest converts them to time which the network stack was
-// blocked on each state.
 struct NET_EXPORT LoadTimingInfo {
   // Contains the LoadTimingInfo events related to establishing a connection.
   // These are all set by ConnectJobs.
@@ -136,6 +141,12 @@ struct NET_EXPORT LoadTimingInfo {
 
   // The time at which the end of the HTTP headers were received.
   base::TimeTicks receive_headers_end;
+
+  // In case the resource was proactively pushed by the server, these are
+  // the times that push started and ended. Note that push_end will be null
+  // if the request is still being pushed.

[mmenke, 2016/04/11 17:45:52]

If the request is still being pushed?  Once we create a URLRequest around the
request, is it still being pushed, or is it now being pulled?

[caseq, 2016/04/13 21:48:45]

Well, that probably depends on how you look on it, but if you look at the wire,
nothing changes when a push stream gets claimed -- i.e. server-initiated push
stream remains as such. So I'd  say it's still being pushed.

[mmenke, 2016/04/14 15:50:33]

Think the comment needs to be clearer.  Just reading it, I still have no idea
when it's no longer null.

+  base::TimeTicks push_start;
+  base::TimeTicks push_end;
 };
 
 }  // namespace net