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 35 matching lines @@
   # Compile in such a way as to make it possible for the profiler to unwind full
   # stack frames. Setting this flag has a large effect on the performance of the
   # generated code than just setting profiling, but gives the profiler more
   # information to analyze.
   # Requires profiling to be set to true.
   enable_full_stack_frames_for_profiling = false
 
   # TODO(GYP): We should be using 64-bit gold for linking on both 64-bit Linux
   # and 32-bit linux; 32-bit Gold runs out of address-space on 32-bit builds.
   # However, something isn't quite working right on the 32-bit builds.
-  use_gold = is_linux && current_cpu == "x64"
+  use_gold = is_linux && (current_cpu == "x64" || current_cpu == "arm")
 
   # When we are going to use gold we need to find it.
   # This is initialized below, after use_gold might have been overridden.
   gold_path = false
 
   # use_debug_fission: whether to use split DWARF debug info
   # files. This can reduce link time significantly, but is incompatible
   # with some utilities such as icecc and ccache. Requires gold and
   # gcc >= 4.8 or clang.
   # http://gcc.gnu.org/wiki/DebugFission
@@ skipping 479 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",

[Mark Seaborn, 2015/12/03 20:02:18]

FYI, this doesn't match the Gyp build exactly.  Here's a fix:
https://codereview.chromium.org/1493753004/

         ]
         ldflags += [
           "-arch",
           "arm-nonsfi",
         ]
       }
     }
   }
 
   asmflags = cflags
@@ skipping 742 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)
   }
 }