android: Add a way to override build system variables.

test/android/gyptest-settings.py

Index: test/android/gyptest-settings.py
diff --git a/test/android/gyptest-settings.py b/test/android/gyptest-settings.py
new file mode 100755
index 0000000000000000000000000000000000000000..f4e89d1bb48b8acdf8613a2ef55d9521629383c9
--- /dev/null
+++ b/test/android/gyptest-settings.py
@@ -0,0 +1,24 @@
+#!/usr/bin/env python
+
+# Copyright (c) 2014 Google Inc. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""
+Verifies that it's possible to set Android build system settings using the
+aosp_build_settings key.
+"""
+
+import TestGyp
+
+test = TestGyp.TestGyp(formats=['android'])
+
+test.run_gyp('settings.gyp')
+
+test.build('settings.gyp', 'hello')
+
+test.run_built_executable('hello.foo', stdout="Hello, world!\n")
+
+test.up_to_date('settings.gyp', test.DEFAULT)
+
+test.pass_test()