Linux: Remove some unused NPAPI code.

content/content_tests.gypi

 # Copyright (c) 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.
 
 {
   'targets': [
     {
       'target_name': 'layouttest_support_content',
       'type': 'static_library',
       'conditions': [
@@ skipping 872 matching lines @@
         ['use_aura!=1 and OS!="android"', {
           'sources!': [
             'browser/renderer_host/input/tap_suppression_controller_unittest.cc',
           ],
         }],
         ['use_dbus==0', {
           'sources!': [
             'browser/geolocation/wifi_data_provider_linux_unittest.cc',
           ],
         }],
+        ['OS!="win" and OS!="mac"', {
+          'sources!': [
+            'common/plugin_list_unittest.cc',
+          ],
+        }],
       ],
     },
   ],
   'conditions': [
     ['test_isolation_mode != "noop"', {
       'targets': [
         {
           'target_name': 'content_unittests_run',
           'type': 'none',
           'dependencies': [
@@ skipping 915 matching lines @@
                   'files': ['<(PRODUCT_DIR)/libnpapi_test_plugin.so'],
                 },
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }