Log force-alt-protocols command line flag usage.

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 efa8f53112e22fb1515c93e502e56b18a9d3c136..a990228fc3777e2984ab0d6ddefc9b43b9a0e8c4 100644
--- a/chrome/browser/io_thread.cc
+++ b/chrome/browser/io_thread.cc
@@ -15,6 +15,7 @@
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/metrics/field_trial.h"
+#include "base/metrics/user_metrics.h"
 #include "base/prefs/pref_registry_simple.h"
 #include "base/prefs/pref_service.h"
 #include "base/stl_util.h"
@@ -909,6 +910,7 @@ void IOThread::EnableSpdy(const std::string& mode) {
       globals_->use_alternate_protocols.set(false);
     } else if (option == kForceAltProtocols) {
       net::AlternateProtocolInfo pair(443, net::NPN_SPDY_3, 1);
+      base::RecordAction(base::UserMetricsAction("Net.ForceAlternateProtocol"));
       net::HttpServerPropertiesImpl::ForceAlternateProtocol(pair);
     } else if (option == kSingleDomain) {
       DVLOG(1) << "FORCING SINGLE DOMAIN";