Add Android NDK build for WebRTC

masters/master.client.webrtc/slaves.cfg

 # Copyright (c) 2012 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.
 
 slaves = [
-  # Linux
+  # Linux.
   {
     'master': 'WebRTC',
     'os': 'linux',
     'version': 'lucid',
     'bits': '64',
     'builder': ['Linux32Debug', 'Linux32Release'],
     'hostname': 'vm305-m3',
   },
   {
     'master': 'WebRTC',
@@ skipping 17 matching lines @@
     'version': 'lucid',
     'bits': '64',
     'builder': ['LinuxTsan', 'LinuxAsan'],
     'hostname': 'vm308-m3',
   },
   {
     'master': 'WebRTC',
     'os': 'linux',
     'version': 'lucid',
     'bits': '64',
-    'builder': ['CrOS'],
+    'builder': ['CrOS', 'Android NDK'],
     'hostname': 'vm310-m3',
   },
-  # Mac
+
+  # Mac.
   {
     'master': 'WebRTC',
     'os': 'mac',
     'version': '10.8',
     'bits': '64',
     'builder': ['Mac32Debug'],
     'hostname': 'vm672-m3',
   },
   {
     'master': 'WebRTC',
     'os': 'mac',
     'version': '10.8',
     'bits': '64',
     'builder': ['Mac32Release'],
     'hostname': 'vm673-m3',
   },
   {
     'master': 'WebRTC',
     'os': 'mac',
     'version': '10.8',
     'bits': '64',
     'builder': ['MacAsan'],
     'hostname': 'vm674-m3',
   },
-  # Windows
+
+  # Windows.
   {
     'master': 'WebRTC',
     'os': 'win',
     'version': 'win7',
     'bits': '64',
     'builder': ['Win32Debug', 'Win32Release'],
     'hostname': 'vm303-m3',
   },
 ]