NoTransportImageTransportFactory is compiled into only test targets.

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 301 matching lines @@
             '../build/linux/system.gyp:glib',
           ],
         }],
         ['use_aura==1', {
           'dependencies': [
             '../ui/aura/aura.gyp:aura_test_support',
             '../ui/resources/ui_resources.gyp:ui_test_pak',
             '../ui/wm/wm.gyp:wm',
           ],
         }],
         ['use_aura==1 or OS=="mac"', {

[Nico, 2014/07/03 19:49:04]

Is this the same as OS!="android" and OS!="ios" below? Should the two blocks
just be collapsed then?

+          'sources': [
+            'browser/compositor/no_transport_image_transport_factory.cc',
+            'browser/compositor/no_transport_image_transport_factory.h',
+          ],
           'dependencies': [
             '../ui/compositor/compositor.gyp:compositor',
           ],
         }],
         ['OS=="win"', {
           'dependencies': [
             '../third_party/iaccessible2/iaccessible2.gyp:iaccessible2',
           ],
         }],
         ['OS!="android" and OS!="ios"', {
@@ skipping 1502 matching lines @@
                   'files': ['<(PRODUCT_DIR)/libnpapi_test_plugin.so'],
                 },
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }