Port r288424 to gn.

build/config/android/config.gni

 # Copyright 2014 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.
 
 # This file contains common system config stuff for the Android build.
 
 if (is_android) {
   declare_args() {
     # Absolute directory containing the Android source code.
     android_src = ""
@@ skipping 69 matching lines @@
   # a "bin" directory inside of these.
   _android_toolchain_version = "4.8"
   x86_android_toolchain_root = "$android_ndk_root/toolchains/x86-${_android_toolchain_version}/prebuilt/${android_host_os}-${android_host_arch}"
   arm_android_toolchain_root = "$android_ndk_root/toolchains/arm-linux-androideabi-${_android_toolchain_version}/prebuilt/${android_host_os}-${android_host_arch}"
   mips_android_toolchain_root = "$android_ndk_root/toolchains/mipsel-linux-android-${_android_toolchain_version}/prebuilt/${android_host_os}-${android_host_arch}"
 
   # Location of libgcc. This is only needed for the current GN toolchain, so we
   # only need to define the current one, rather than one for every platform
   # like the toolchain roots.
   if (cpu_arch == "x86") {
+    android_toolchain_root = "$x86_android_toolchain_root"
     android_libgcc_file =
-      "$x86_android_toolchain_root/lib/gcc/i686-linux-android/${_android_toolchain_version}/libgcc.a"
+      "$android_toolchain_root/lib/gcc/i686-linux-android/${_android_toolchain_version}/libgcc.a"
   } else if (cpu_arch == "arm") {
+    android_toolchain_root = "$arm_android_toolchain_root"
     android_libgcc_file =
-      "$arm_android_toolchain_root/lib/gcc/arm-linux-androideabi/${_android_toolchain_version}/libgcc.a"
+      "$android_toolchain_root/lib/gcc/arm-linux-androideabi/${_android_toolchain_version}/libgcc.a"
   } else if (cpu_arch == "mipsel") {
+    android_toolchain_root = "$mips_android_toolchain_root"
     android_libgcc_file =
-      "$mips_android_toolchain_root/lib/gcc/mipsel-linux-android/${_android_toolchain_version}/libgcc.a"
+      "$android_toolchain_root/lib/gcc/mipsel-linux-android/${_android_toolchain_version}/libgcc.a"
   } else {
     assert(false, "Need android libgcc support for your target arch.")
   }
 
   # stlport stuff --------------------------------------------------------------
 
   use_system_stlport = is_android_webview_build
 
   if (use_system_stlport) {
     android_stlport_library = "stlport"
@@ skipping 18 matching lines @@
     android_app_abi = "mips"
   } else {
     assert(false, "Unknown Android ABI: " + cpu_arch)
   }
 } else {
   if (!defined(is_android_webview_build)) {
     is_android_webview_build = false
   }
   use_system_stlport = false
 }