use MEDIA_BLINK_EXPORT in media/blink

media/blink/media_blink.gyp

 # Copyright 2014 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.
 
 {
   'includes': [
     '../media_variables.gypi'
   ],
   'targets': [
     {
       # GN version: //media/blink
       'target_name': 'media_blink',
       'type': '<(component)',
       'dependencies': [
         '../../base/base.gyp:base',
         '../../cc/cc.gyp:cc',
         '../../cc/blink/cc_blink.gyp:cc_blink',
         '../../gpu/blink/gpu_blink.gyp:gpu_blink',
         '../../ui/gfx/gfx.gyp:gfx_geometry',
         '../../net/net.gyp:net',
         '../../skia/skia.gyp:skia',
         '../../third_party/WebKit/public/blink.gyp:blink',
         '../media.gyp:media',
         '../media.gyp:shared_memory_support',
         '../../url/url.gyp:url_lib',
       ],
       'defines': [
-        'MEDIA_IMPLEMENTATION',
+        'MEDIA_BLINK_IMPLEMENTATION',
       ],
       # This sources list is duplicated in //media/blink/BUILD.gn
       'sources': [
         'active_loader.cc',
         'active_loader.h',
         'buffered_data_source.cc',
         'buffered_data_source.h',
         'buffered_data_source_host_impl.cc',
         'buffered_data_source_host_impl.h',
         'buffered_resource_loader.cc',
         'buffered_resource_loader.h',
         'cache_util.cc',
         'cache_util.h',
         'cdm_result_promise.h',
         'cdm_result_promise_helper.cc',
         'cdm_result_promise_helper.h',
         'cdm_session_adapter.cc',
         'cdm_session_adapter.h',
         'encrypted_media_player_support.cc',
         'encrypted_media_player_support.h',
         'key_system_config_selector.cc',
         'key_system_config_selector.h',
+        'media_blink_export.h',
         'new_session_cdm_result_promise.cc',
         'new_session_cdm_result_promise.h',
         'texttrack_impl.cc',
         'texttrack_impl.h',
         'video_frame_compositor.cc',
         'video_frame_compositor.h',
         'webaudiosourceprovider_impl.cc',
         'webaudiosourceprovider_impl.h',
         'webcontentdecryptionmodule_impl.cc',
         'webcontentdecryptionmodule_impl.h',
@@ skipping 90 matching lines @@
                   '../../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
                 ],
               }
             ],
           ],
         },
       ],
     }],
   ],
 }