Add commandline flag for service workers.

content/public/common/content_switches.cc

Index: content/public/common/content_switches.cc
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index b6a1704f3a03ecf09eef922be978f24ca7d875f8..8ca766f0a7462cd9637a754343be8cfc7d9eba80 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -523,6 +523,10 @@ const char kEnableStatsTable[]              = "enable-stats-table";
 // cookies on cross-site requests.
 const char kEnableStrictSiteIsolation[]     = "enable-strict-site-isolation";
 
+// Enable support for ServiceWorker. See
+// https://github.com/slightlyoff/ServiceWorker for more information.
+const char kEnableServiceWorker[]           = "enable-service-worker";
+
 // Enable use of experimental TCP sockets API for sending data in the
 // SYN packet.
 const char kEnableTcpFastOpen[]             = "enable-tcp-fastopen";