Work on Android GN build.

build/toolchain/android/BUILD.gn

 # Copyright 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("../clang.gni")
-import("../goma.gni")
-import("../gcc_toolchain.gni")
-
-# Get the location of the Android tools in our tree.
-android_ndk_root =
-  rebase_path("//third_party/android_tools/ndk", ".", "")
+import("//build/config/android/config.gni")
+import("//build/toolchain/clang.gni")
+import("//build/toolchain/goma.gni")
+import("//build/toolchain/gcc_toolchain.gni")
 
 # Get the Android version of the name of the build host's architecture.
 if (build_cpu_arch == "x64") {
   android_host_arch = "x86_64"
 } else if (build_cpu_arch == "x86") {
   android_host_arch = "x86"
 } else {
   assert(false, "Need Android toolchain support for your build OS.")
 }
 
@@ skipping 83 matching lines @@
 gcc_toolchain("mipsel") {
   prefix = "$android_ndk_root/toolchains/mipsel-linux-android-4.6/prebuilt/$build_os-$android_host_arch/bin/mipsel-linux-android-"
   cc  = prefix + "gcc"
   cxx = prefix + "g++"
   ar  = prefix + "ar"
   ld  = cxx
 
   toolchain_cpu_arch = "mipsel"
   toolchain_os = "android"
 }