Separate building and enabling libevent.

webrtc/base/base.gyp

 # Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 {
   'includes': [ '../build/common.gypi', ],
@@ skipping 66 matching lines @@
         'safe_conversions_impl.h',
         'scoped_ref_ptr.h',
         'stringencode.cc',
         'stringencode.h',
         'stringutils.cc',
         'stringutils.h',
         'swap_queue.h',
         'systeminfo.cc',
         'systeminfo.h',
         'task_queue.h',
-        'task_queue_libevent.cc',
-        'task_queue_gcd.cc',
-        'task_queue_posix.cc',
         'task_queue_posix.h',
-        'task_queue_win.cc',
         'template_util.h',
         'thread_annotations.h',
         'thread_checker.h',
         'thread_checker_impl.cc',
         'thread_checker_impl.h',
         'timeutils.cc',
         'timeutils.h',
         'trace_event.h',
       ],
       'conditions': [
@@ skipping 12 matching lines @@
           'sources': [
             'logging.cc',
             'logging.h',
             'logging_mac.mm',
           ],
         }],
         ['build_libevent==1', {
           'dependencies': [
             '<(DEPTH)/base/third_party/libevent/libevent.gyp:libevent',
           ],
+        }],
+        ['enable_libevent==1', {
+          'sources': [
+            'task_queue_libevent.cc',
+            'task_queue_posix.cc',
+          ],
         }, {
-          'sources!': [ 'task_queue_libevent.cc' ],
+          # If not libevent, fall back to the other task queues.
           'conditions': [
-            ['OS=="linux" or OS=="android"', {
-              'sources!': [ 'task_queue_posix.cc' ],
+            ['OS=="mac" or OS=="ios"', {
+             'sources': [
+               'task_queue_gcd.cc',
+               'task_queue_posix.cc',
+             ],
             }],
+            ['OS=="win"', {
+              'sources': [ 'task_queue_win.cc' ],
+            }]
           ],
         }],
-        ['build_libevent==1 or OS=="linux" or OS=="android" or OS=="win"', {
-          'sources!': [ 'task_queue_gcd.cc' ],
-        }],
         ['OS=="mac" and build_with_chromium==0', {
           'all_dependent_settings': {
             'xcode_settings': {
               'OTHER_LDFLAGS': [
                 # needed for logging_mac.mm
                 '-framework Foundation',
               ],
             },
           },
         }], # OS=="mac" and build_with_chromium==0
@@ skipping 476 matching lines @@
     },
     {
      'target_name': 'gtest_prod',
       'type': 'static_library',
       'sources': [
         'gtest_prod_util.h',
       ],
     },
   ],
 }