Synchronize GN build configuration with Chrome

build/toolchain/nacl_toolchain.gni

Index: build/toolchain/nacl_toolchain.gni
diff --git a/build/toolchain/nacl_toolchain.gni b/build/toolchain/nacl_toolchain.gni
index a07620dbfcac4740beb5dc23abcb2efd17e7d610..c851885c0c43fd101762b9091d9208407d727b97 100644
--- a/build/toolchain/nacl_toolchain.gni
+++ b/build/toolchain/nacl_toolchain.gni
@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/nacl/config.gni")
 import("//build/toolchain/gcc_toolchain.gni")
 
 # This template defines a NaCl toolchain.
@@ -42,10 +43,11 @@ template("nacl_toolchain") {
                              "ld",
                              "link_outputs",
                              "postlink",
+                             "symbol_level",
                              "toolchain_cpu",
                            ])
 
-    # We do not suport component builds or sanitizers with the NaCl toolchains.
+    # We do not suport component builds with the NaCl toolchains.
     is_component_build = false
 
     rebuild_define = "NACL_TC_REV=" + invoker.toolchain_revision