Allow building without notification support.

content/content_renderer.gypi

 # Copyright (c) 2011 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.
 
 {
   'dependencies': [
     '../jingle/jingle.gyp:jingle_glue',
     '../net/net.gyp:net',
     '../ppapi/ppapi_internal.gyp:ppapi_proxy',
     '../skia/skia.gyp:skia',
@@ skipping 209 matching lines @@
           'dependencies': [
               '../base/allocator/allocator.gyp:allocator',
           ],
         }],
         ['input_speech==0', {
           'sources!': [
             'renderer/speech_input_dispatcher.cc',
             'renderer/speech_input_dispatcher.h',
           ]
         }],
+        ['notifications==0', {
+          'sources!': [
+            'renderer/notification_provider.cc',
+            'renderer/active_notification_tracker.cc',
+          ],
+        }],
       ],
       'dependencies': [
         '../build/linux/system.gyp:gtk',
       ],
     }],
     ['OS=="mac"', {
       'sources!': [
         'common/process_watcher_posix.cc',
       ],
       'link_settings': {
@@ skipping 28 matching lines @@
     }, {
       'sources!': [
         'renderer/java_bridge_channel.cc',
         'renderer/java_bridge_channel.h',
         'renderer/java_bridge_dispatcher.cc',
         'renderer/java_bridge_dispatcher.h',
       ],
     }],
   ],
 }