Use AOM_USAGE_REALTIME in realtime only config

In the EncodeAPI.SetSFrameOnFirstFrame test, pass kUsage to the
aom_codec_enc_config_default() call.

Bug: aomedia:3216, aomedia:3218
Change-Id: Ib6feff49de8ca9da875d9cb57ec93d33f1e6ab37
diff --git a/test/encode_api_test.cc b/test/encode_api_test.cc
index c37ea1a..8303880 100644
--- a/test/encode_api_test.cc
+++ b/test/encode_api_test.cc
@@ -22,9 +22,9 @@
 namespace {
 
 #if CONFIG_REALTIME_ONLY
-const int kUsage = 1;
+const int kUsage = AOM_USAGE_REALTIME;
 #else
-const int kUsage = 0;
+const int kUsage = AOM_USAGE_GOOD_QUALITY;
 #endif
 
 TEST(EncodeAPI, InvalidParams) {
@@ -92,7 +92,7 @@
 
   aom_codec_iface_t *iface = aom_codec_av1_cx();
   aom_codec_enc_cfg_t cfg;
-  ASSERT_EQ(aom_codec_enc_config_default(iface, &cfg, 0), AOM_CODEC_OK);
+  ASSERT_EQ(aom_codec_enc_config_default(iface, &cfg, kUsage), AOM_CODEC_OK);
   cfg.g_w = kWidth;
   cfg.g_h = kHeight;