use MEDIA_BLINK_EXPORT in media/blink

media/blink/BUILD.gn

 # 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.
 
 import("//media/media_options.gni")
 import("//testing/test.gni")
 
 component("blink") {
   output_name = "media_blink"
 
   deps = [
     "//base",
     "//cc",
     "//cc/blink",
     "//gpu/blink",
     "//media",
     "//media:shared_memory_support",
     "//net",
     "//skia",
     "//third_party/WebKit/public:blink",
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//url",
   ]
 
-  defines = [ "MEDIA_IMPLEMENTATION" ]
+  defines = [ "MEDIA_BLINK_IMPLEMENTATION" ]
 
   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",
     "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 74 matching lines @@
 }
 
 # TODO(GYP): Delete this after we've converted everything to GN.
 # The _run targets exist only for compatibility w/ GYP.
 group("media_blink_unittests_run") {
   testonly = true
   deps = [
     ":media_blink_unittests",
   ]
 }