[GCM] Add port 443 fallback logic and histograms

google_apis/gcm/tools/mcs_probe.cc

Index: google_apis/gcm/tools/mcs_probe.cc
diff --git a/google_apis/gcm/tools/mcs_probe.cc b/google_apis/gcm/tools/mcs_probe.cc
index 48815df589281c12b4134b4133d9accb458d070b..157a73f355f9289f9c6aa312d2d04667b3f7bdf1 100644
--- a/google_apis/gcm/tools/mcs_probe.cc
+++ b/google_apis/gcm/tools/mcs_probe.cc
@@ -290,9 +290,12 @@ void MCSProbe::Start() {
   file_thread_.Start();
   InitializeNetworkState();
   BuildNetworkSession();
+  std::vector<GURL> endpoints(1,
+                              GURL("https://" +
+                                   net::HostPortPair(server_host_,
+                                                     server_port_).ToString()));
   connection_factory_.reset(
-      new ConnectionFactoryImpl(GURL("https://" + net::HostPortPair(
-                                    server_host_, server_port_).ToString()),
+      new ConnectionFactoryImpl(endpoints,
                                 kDefaultBackoffPolicy,
                                 network_session_,
                                 &net_log_));