Added --disable-ipv4 and --disable-ipv6 switches. By default both enabled.

cloud_print/gcp20/prototype/gcp20_switches.cc

Index: cloud_print/gcp20/prototype/gcp20_switches.cc
diff --git a/cloud_print/gcp20/prototype/gcp20_switches.cc b/cloud_print/gcp20/prototype/gcp20_switches.cc
index cce7eaf0d842e8fedf3b5bbd5cc13e8dfba82e92..dfb425c9f1638dc20bc8c280484a34715eed2387 100644
--- a/cloud_print/gcp20/prototype/gcp20_switches.cc
+++ b/cloud_print/gcp20/prototype/gcp20_switches.cc
@@ -10,6 +10,8 @@
 namespace switches {
 
 const char kDisableConfirmation[] = "disable-confirmation";
+const char kDisableIpv4[] = "disable-ipv4";
+const char kDisableIpv6[] = "disable-ipv6";
 const char kDisableMethodCheck[] = "disable-method-check";
 const char kDisableXTocken[] = "disable-x-token";
 const char kDomainName[] = "domain-name";
@@ -30,13 +32,15 @@ const struct {
   const char* const arg;
 } kHelpStrings[] = {
   {kDisableConfirmation, "disables confirmation of registration", NULL},
+  {kDisableIpv4, "disables IPv4 support", NULL},
+  {kDisableIpv6, "disables IPv6 support", NULL},
   {kDisableMethodCheck, "disables HTTP method checking (POST, GET)", NULL},
   {kDisableXTocken, "disables checking of X-Privet-Token HTTP header", NULL},
   {kNoAnnouncement, "disables DNS announcements", NULL},
   {kExtendedResponce, "responds to PTR with additional records", NULL},
   {kSimulatePrintingErrors, "simulates some errors for local printing", NULL},
   {kUnicastRespond,
-    "DNS responses will be sent in unicast instead of multicast", NULL},
+       "DNS responses will be sent in unicast instead of multicast", NULL},
   {kDomainName, "sets, should ends with '.local'", "DOMAIN"},
   {kHttpPort, "sets port for HTTP server", "PORT"},
   {kServiceName, "sets DNS service name", "SERVICE"},