[AUTO UPDATE] Copying from upstream Mojo Repository.
d62de1a8ac7603c85917df9149578e22acfa2d0b
  Mon, 20 Jun 2016 09:53:50 -0700, jamesr@chromium.org
  Roll buildtools to 3780bc523aad1d68a5bd00e05c453a80b2ba0b35

toolchain/gcc_toolchain.gni

diff --git a/toolchain/gcc_toolchain.gni b/toolchain/gcc_toolchain.gni
index 3e7bc53..08ff51f 100644
--- a/toolchain/gcc_toolchain.gni
+++ b/toolchain/gcc_toolchain.gni
@@ -275,15 +275,22 @@
       target_os = target_os
       target_cpu = target_cpu
 
-      forward_variables_from(invoker,
-                             [
-                               "is_clang",
-                               "is_pnacl",
-                               "is_component_build",
-                               "is_nacl_glibc",
-                               "use_gold",
-                               "symbol_level",
-                             ])
+      forward_variables_from(invoker, [ "use_gold" ])
+      if (defined(invoker.is_clang)) {
+        is_clang = invoker.is_clang
+      }
+      if (defined(invoker.is_pnacl)) {
+        is_pnacl = invoker.is_pnacl
+      }
+      if (defined(invoker.is_component_build)) {
+        is_component_build = invoker.is_component_build
+      }
+      if (defined(invoker.is_nacl_glibc)) {
+        is_nacl_glibc = invoker.is_nacl_glibc
+      }
+      if (defined(invoker.symbol_level)) {
+        symbol_level = invoker.symbol_level
+      }
     }
 
     forward_variables_from(invoker, [ "deps" ])

toolchain/nacl_toolchain.gni

diff --git a/toolchain/nacl_toolchain.gni b/toolchain/nacl_toolchain.gni
index 218e064..68b46a0 100644
--- a/toolchain/nacl_toolchain.gni
+++ b/toolchain/nacl_toolchain.gni
@@ -38,15 +38,23 @@
                              "cc",
                              "cxx",
                              "deps",
-                             "is_clang",
-                             "is_pnacl",
-                             "is_nacl_glibc",
                              "ld",
                              "link_outputs",
                              "postlink",
-                             "symbol_level",
                              "toolchain_cpu",
                            ])
+    if (defined(invoker.is_clang)) {
+      is_clang = invoker.is_clang
+    }
+    if (defined(invoker.is_pnacl)) {
+      is_pnacl = invoker.is_pnacl
+    }
+    if (defined(invoker.is_nacl_glibc)) {
+      is_nacl_glibc = invoker.is_nacl_glibc
+    }
+    if (defined(invoker.symbol_level)) {
+      symbol_level = invoker.symbol_level
+    }
 
     # We do not suport component builds with the NaCl toolchains.
     is_component_build = false