Add a way for CrOS toolchains to set custom flags for the nacl bootstrap.

build/toolchain/cros/BUILD.gn

Index: build/toolchain/cros/BUILD.gn
diff --git a/build/toolchain/cros/BUILD.gn b/build/toolchain/cros/BUILD.gn
index 56a408bfd35e1d790b8ac14b736eac7fb43849bf..bf139dc12da8192f02bd1e7c83e18c3a77f795a5 100644
--- a/build/toolchain/cros/BUILD.gn
+++ b/build/toolchain/cros/BUILD.gn
@@ -7,58 +7,65 @@ import("//build/config/sysroot.gni")
 import("//build/toolchain/gcc_toolchain.gni")
 import("//build/toolchain/cros_toolchain.gni")
 
-template("cros_target_toolchain") {
-  gcc_toolchain(target_name) {
-    assert(defined(invoker.toolchain_args))
-
-    # These are args for the template.
-    ar = cros_target_ar
-    cc = cros_target_cc
-    cxx = cros_target_cxx
-    ld = cxx
-    if (cros_target_ld != "") {
-      ld = cros_target_ld
-    }
-    if (cros_target_nm != "") {
-      nm = cros_target_nm
-    }
-    if (cros_target_readelf != "") {
-      readelf = cros_target_readelf
-    }
-    extra_cflags = cros_target_extra_cflags
-    extra_cppflags = cros_target_extra_cppflags
-    extra_cxxflags = cros_target_extra_cxxflags
-    extra_ldflags = cros_target_extra_ldflags
-
-    toolchain_args = {
-      forward_variables_from(invoker.toolchain_args, "*")
-
-      cc_wrapper = ""
-
-      # This will override the default computation for is_clang in the
-      # secondary toolchain with the value of is_clang in the current toolchain
-      # (the current toolchain will always be the default toolchain here).
-      is_clang = is_clang
-      current_cpu = target_cpu
-      current_os = "chromeos"
-      use_debug_fission = use_debug_fission
-      use_sysroot = use_sysroot
-    }
+# This is the normal toolchain for most targets.
+gcc_toolchain("target") {
+  ar = cros_target_ar
+  cc = cros_target_cc
+  cxx = cros_target_cxx
+  ld = cxx
+  if (cros_target_ld != "") {
+    ld = cros_target_ld
   }
-}
+  if (cros_target_nm != "") {
+    nm = cros_target_nm
+  }
+  if (cros_target_readelf != "") {
+    readelf = cros_target_readelf
+  }
+  extra_cflags = cros_target_extra_cflags
+  extra_cppflags = cros_target_extra_cppflags
+  extra_cxxflags = cros_target_extra_cxxflags
+  extra_ldflags = cros_target_extra_ldflags
 
-# This is the normal toolchain for most targets.
-cros_target_toolchain("target") {
   toolchain_args = {
+    cc_wrapper = ""
+    current_cpu = target_cpu
+    current_os = "chromeos"
+    is_clang = is_clang
+    use_debug_fission = use_debug_fission
+    use_gold = use_gold
+    use_sysroot = use_sysroot
   }
 }
 
 # This is a special toolchain needed just for the nacl_bootstrap target in
 # //native_client/src/trusted/service_runtime/linux. It is identical
 # to ":target" except that it forces use_debug_fission, use_gold, and
-# use_sysroot off.
-cros_target_toolchain("nacl_bootstrap") {
+# use_sysroot off, and allows the user to set different sets of extra flags.
+gcc_toolchain("nacl_bootstrap") {
+  ar = cros_target_ar
+  cc = cros_target_cc
+  cxx = cros_target_cxx
+  ld = cxx
+  if (cros_target_ld != "") {
+    ld = cros_target_ld
+  }
+  if (cros_target_nm != "") {
+    nm = cros_target_nm
+  }
+  if (cros_target_readelf != "") {
+    readelf = cros_target_readelf
+  }
+  extra_cflags = cros_nacl_bootstrap_extra_cflags
+  extra_cppflags = cros_nacl_bootstrap_extra_cppflags
+  extra_cxxflags = cros_nacl_bootstrap_extra_cxxflags
+  extra_ldflags = cros_nacl_bootstrap_extra_ldflags
+
   toolchain_args = {
+    cc_wrapper = ""
+    current_cpu = target_cpu
+    current_os = "chromeos"
+    is_clang = is_clang
     use_debug_fission = false
     use_gold = false
     use_sysroot = false