Use _target_name instead of package_name for java*.gypi

tools/android/findbugs_plugin/findbugs_plugin.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': 'findbugs_plugin_test',
          'type': 'none',
          'variables': {
-           'package_name': 'findbugs_plugin',
            'java_in_dir': 'test/java/',
          },
          'includes': [ '../../../build/java.gypi' ],
       }
    ]
 }