Enable arm/linux chromium to build with gn

build/config/compiler/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/config.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/nacl/config.gni")
 import("//build/toolchain/ccache.gni")
 
@@ skipping 539 matching lines @@
         ldflags += [
           "-arch",
           "x86-32-nonsfi",
           "--target=i686-unknown-nacl",
         ]
       } else if (target_cpu == "arm") {
         cflags += [
           "-arch",
           "arm-nonsfi",
           "--pnacl-bias=arm-nonsfi",
+          "--target=arm-unknown-nacl",
         ]
         ldflags += [
           "-arch",
           "arm-nonsfi",
         ]
       }
     }
   }
 
   asmflags = cflags
@@ skipping 748 matching lines @@
   if (symbol_level == 0) {
     configs = [ ":no_symbols" ]
   } else if (symbol_level == 1) {
     configs = [ ":minimal_symbols" ]
   } else if (symbol_level == 2) {
     configs = [ ":symbols" ]
   } else {
     assert(false)
   }
 }