Improve GCM enum switch type safety

components/gcm_driver/gcm_desktop_utils.cc

Index: components/gcm_driver/gcm_desktop_utils.cc
diff --git a/components/gcm_driver/gcm_desktop_utils.cc b/components/gcm_driver/gcm_desktop_utils.cc
index ce9994575a79ad946058bc54658407bcd23f7c35..ec566ead27f8788d9ea1d25bad12bb2587344bfa 100644
--- a/components/gcm_driver/gcm_desktop_utils.cc
+++ b/components/gcm_driver/gcm_desktop_utils.cc
@@ -53,10 +53,9 @@ GCMClient::ChromeChannel GetChannel(version_info::Channel channel) {
       return GCMClient::CHANNEL_BETA;
     case version_info::Channel::STABLE:
       return GCMClient::CHANNEL_STABLE;
-    default:
-      NOTREACHED();
-      return GCMClient::CHANNEL_UNKNOWN;
   }
+  NOTREACHED();
+  return GCMClient::CHANNEL_UNKNOWN;
 }
 
 std::string GetVersion() {