media: Use "public_configs" for "mojo_media_config"

content/renderer/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("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//content/renderer/renderer.gni")
 import("//media/media_options.gni")
 
 source_set("renderer") {
@@ skipping 212 matching lines @@
   }
 
   if (enable_mojo_media) {
     sources += [
       "media/media_interface_provider.cc",
       "media/media_interface_provider.h",
     ]
 
     deps += [
       "//media/mojo/interfaces",
+
+      # Defines in mojo_media_config are also pulled in here.
       "//media/mojo/services:proxy",
     ]
   }
 
   if (enable_webvr) {
     sources += [
       "vr/vr_dispatcher.cc",
       "vr/vr_dispatcher.h",
       "vr/vr_type_converters.cc",
       "vr/vr_type_converters.h",
     ]
   }
 
   if (use_seccomp_bpf) {
     defines += [ "USE_SECCOMP_BPF" ]
   }
 
   if (use_ozone) {
     deps += [ "//ui/ozone" ]
   }
 }
 
 # See comment at the top of //content/BUILD.gn for how this works.
 group("for_content_tests") {
   visibility = [ "//content/test/*" ]
+
+  if (enable_mojo_media) {
+    # For the defines in mojo_media_config.
+    public_configs = [ "//media/mojo/services:mojo_media_config" ]
+  }
+
   if (!is_component_build) {
     public_deps = [
       ":renderer",
     ]
   }
 }