Add templates for building java and running the jni_generator.

base/android/java/java.gyp

-# 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.
-
-{
-  'targets': [
-    {
-      'target_name': 'base_java',
-      'message': 'building base java sources',
-      'type': 'none',
-      'actions': [
-        {
-          'action_name': 'base_java',
-          'inputs': [
-            '<(DEPTH)/base/android/java/base.xml',
-            '<!@(find . -name "*.java")'
-          ],
-          'outputs': [
-            '<(DEPTH)/base/android/java/dist/lib/chromium_base.jar',
-          ],
-          'action': [
-            'ant',
-            '-buildfile',
-            '<(DEPTH)/base/android/java/base.xml',
-          ]
-        },
-      ],
-    },
-  ],
-}