Fix "unused variable" warnings.

media/mojo/services/service_factory_impl.h

Index: media/mojo/services/service_factory_impl.h
diff --git a/media/mojo/services/service_factory_impl.h b/media/mojo/services/service_factory_impl.h
index aec2cb1c06e95d4e310db90421c1088272bdc4e0..fe9af8f59281af82cbad615cb9203d7b1950f9eb 100644
--- a/media/mojo/services/service_factory_impl.h
+++ b/media/mojo/services/service_factory_impl.h
@@ -58,10 +58,15 @@ class ServiceFactoryImpl : public mojom::ServiceFactory {
 
   MojoCdmServiceContext cdm_service_context_;
   mojo::StrongBinding<mojom::ServiceFactory> binding_;
+#if defined(ENABLE_MOJO_CDM)
   shell::mojom::InterfaceProvider* interfaces_;
+#endif
+#if defined(ENABLE_MOJO_AUDIO_DECODER) || defined(ENABLE_MOJO_CDM) || \
+    defined(ENABLE_MOJO_RENDERER)
+  MojoMediaClient* mojo_media_client_;
+#endif
   scoped_refptr<MediaLog> media_log_;
   std::unique_ptr<shell::ShellConnectionRef> connection_ref_;
-  MojoMediaClient* mojo_media_client_;
 
   DISALLOW_COPY_AND_ASSIGN(ServiceFactoryImpl);
 };