Migrating RBE flags to RBE_ variables.

Test: N/A, this only adds new variables.

Change-Id: Iad09352090ec255af82e77941e6e050137f1e83b
diff --git a/ui/build/ninja.go b/ui/build/ninja.go
index 4fc1f01..dfc3be1 100644
--- a/ui/build/ninja.go
+++ b/ui/build/ninja.go
@@ -128,6 +128,16 @@
 			"GOMA_USE_LOCAL",
 
 			// RBE client
+			"RBE_compare",
+			"RBE_exec_root",
+			"RBE_exec_strategy",
+			"RBE_invocation_id",
+			"RBE_log_dir",
+			"RBE_platform",
+			"RBE_remote_accept_cache",
+			"RBE_remote_update_cache",
+			"RBE_server_address",
+			// TODO: remove old FLAG_ variables.
 			"FLAG_compare",
 			"FLAG_exec_root",
 			"FLAG_exec_strategy",