Add video_loopback to gn.

webrtc/webrtc_tests.gypi

 # Copyright (c) 2013 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.
 {
   'targets': [
     {
@@ skipping 259 matching lines @@
           'dependencies!': [
             '<(webrtc_root)/modules/modules.gyp:video_capture_module_internal_impl',
           ],
         }],
       ],
     },
     {
       'target_name': 'video_loopback',
       'type': 'executable',
       'sources': [
-        'test/mac/run_test.mm',
-        'test/run_test.cc',
         'test/run_test.h',
         'video/video_loopback.cc',
       ],
       'conditions': [
         ['OS=="mac"', {
-          'sources!': [
+          'sources': [
+            'test/mac/run_test.mm',
+          ],
+        }, {
+          'sources': [
             'test/run_test.cc',
           ],
         }],
       ],
       'dependencies': [
         'video_quality_test',
         '<(DEPTH)/testing/gtest.gyp:gtest',
         '<(DEPTH)/third_party/gflags/gflags.gyp:gflags',
+        '<(webrtc_root)/system_wrappers/system_wrappers.gyp:metrics_default',
+        'test/test.gyp:field_trial',
         'test/test.gyp:test_common',
-        'test/test.gyp:test_main',
         'test/test.gyp:test_renderer',
-        'webrtc',
       ],
     },
     {
       'target_name': 'screenshare_loopback',
       'type': 'executable',
       'sources': [
         'test/mac/run_test.mm',
         'test/run_test.cc',
         'test/run_test.h',
         'video/screenshare_loopback.cc',
@@ skipping 350 matching lines @@
             'build/isolate.gypi',
           ],
           'sources': [
             'webrtc_perf_tests.isolate',
           ],
         },
       ],
     }],
   ],
 }