[SPDY] Add flag to turn on SPDY/3.1 (with per-session flow control)

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 2bbc47533a54ac4eb50e4965f1a4d8caa6a59d24..c69d77dc75f362ed5d69788fdee83a4e543d5de3 100644
--- a/chrome/browser/io_thread.cc
+++ b/chrome/browser/io_thread.cc
@@ -649,24 +649,20 @@ void IOThread::InitializeNetworkOptions(const CommandLine& command_line) {
   if (command_line.HasSwitch(switches::kIgnoreUrlFetcherCertRequests))
     net::URLFetcher::SetIgnoreCertificateRequests(true);
 
-  bool used_spdy_switch = false;
   if (command_line.HasSwitch(switches::kUseSpdy)) {
     std::string spdy_mode =
         command_line.GetSwitchValueASCII(switches::kUseSpdy);
     EnableSpdy(spdy_mode);
-    used_spdy_switch = true;
-  }
-  if (command_line.HasSwitch(switches::kEnableSpdy3)) {
+  } else if (command_line.HasSwitch(switches::kEnableSpdy31)) {
+    net::HttpStreamFactory::EnableNpnSpdy31();
+  } else if (command_line.HasSwitch(switches::kEnableSpdy3)) {
     net::HttpStreamFactory::EnableNpnSpdy3();
-    used_spdy_switch = true;
   } else if (command_line.HasSwitch(switches::kEnableNpn)) {
     net::HttpStreamFactory::EnableNpnSpdy();
-    used_spdy_switch = true;
   } else if (command_line.HasSwitch(switches::kEnableNpnHttpOnly)) {
     net::HttpStreamFactory::EnableNpnHttpOnly();
-    used_spdy_switch = true;
-  }
-  if (!used_spdy_switch) {
+  } else {
+    // Use SPDY/3 by default.
     net::HttpStreamFactory::EnableNpnSpdy3();
   }
 }