Add Spdy4Experiment group.

chrome/browser/io_thread.cc

Index: chrome/browser/io_thread.cc
diff --git a/chrome/browser/io_thread.cc b/chrome/browser/io_thread.cc
index b84a24ba1b0c41e2546763f887f4ef6dba0efed9..77e878dc15f751783e1f770475e6a5be78d6d7fc 100644
--- a/chrome/browser/io_thread.cc
+++ b/chrome/browser/io_thread.cc
@@ -134,6 +134,7 @@ const char kSpdyFieldTrialName[] = "SPDY";
 const char kSpdyFieldTrialHoldbackGroupName[] = "SpdyDisabled";
 const char kSpdyFieldTrialHoldbackControlGroupName[] = "Control";
 const char kSpdyFieldTrialSpdy4GroupName[] = "Spdy4Enabled";
+const char kSpdyFieldTrialSpdy4ExperimentGroupName[] = "Spdy4Experiment";
 const char kSpdyFieldTrialSpdy4ControlGroupName[] = "Spdy4Control";
 
 // Field trial for Cache-Control: stale-while-revalidate directive.
@@ -844,6 +845,9 @@ void IOThread::ConfigureSpdyFromTrial(const std::string& spdy_trial_group,
   } else if (spdy_trial_group == kSpdyFieldTrialSpdy4GroupName) {

[Ryan Hamilton, 2014/10/30 17:34:32]

We've been doing a lot of finch config work with QUIC lately. An alternative is
to do something like:

if (spdy_trail_group.starts_with(kSpdyFieldTrialSpdy4GroupName) {
  ..
}

Then you can create an unlimited number of different group names without needing
to change the code.  The other thing you could consider would be do something
like we do with QUIC where we make use of params in each field trial group to
control various knobs explicitly, instead of needing to look at/parse out the
group name.

I think it would be better to pursue one of these approaches rather than
hardcoding a new group name in the code.

What do you think?

[Bence, 2014/10/30 18:39:03]

This is a great idea.  I am extenting this to SpdyDisabled, and adding
Spdy31Enabled.  This will allow us to deprecate *Control*, and have a clearer
group layout, like:
* SpdyDisabled-5
* Spdy31Enabled-5
* Spdy4Enabled-5
* Spdy4Enabled-rest

     globals->next_protos = net::NextProtosSpdy4Http2();
     globals->use_alternate_protocols.set(true);
+  } else if (spdy_trial_group == kSpdyFieldTrialSpdy4ExperimentGroupName) {
+    globals->next_protos = net::NextProtosSpdy4Http2();
+    globals->use_alternate_protocols.set(true);
   } else if (spdy_trial_group == kSpdyFieldTrialSpdy4ControlGroupName) {
     // This control group is pinned at SPDY/3.1.
     globals->next_protos = net::NextProtosSpdy31();