media: Convert mojo media defines to buildflags

media/mojo/clients/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.
 
 # Implementations of media C++ interfaces using corresponding mojo services.
 source_set("clients") {
   visibility = [
     "//chromecast/*",
     "//content/renderer",
 
@@ skipping 32 matching lines @@
     "mojo_video_decoder.h",
   ]
 
   if (is_android) {
     sources += [
       "mojo_android_overlay.cc",
       "mojo_android_overlay.h",
     ]
   }
 
-  public_configs = [ "//media/mojo/services:mojo_media_config" ]
-
   public_deps = [
     "//base",
     "//media",
+    "//media/mojo:features",
     "//media/mojo/interfaces",
     "//mojo/public/cpp/bindings",
     "//mojo/public/cpp/system",
     "//services/service_manager/public/interfaces",
   ]
 
   deps = [
     "//media/mojo/common",
     "//mojo/common",
     "//services/service_manager/public/cpp",
   ]
 
   if (is_android) {
     deps += [
       "//gpu/ipc/common:common",
       "//ui/gl:gl",
     ]
   }
 }