Ensure the error-concealment code is available

When it's configured, make sure it can be configured. When it's not,
make sure it fails.

Change-Id: I857d4b8014547ddbad70395f17e58d5838bd142f

test/decode_api_test.cc

@@ -57,6 +57,21 @@ TEST(DecodeAPI, InvalidParams) {
   }
 }
 
+#if CONFIG_VP8_DECODER
+TEST(DecodeAPI, OptionalParams) {
+  vpx_codec_ctx_t dec;
+
+#if CONFIG_ERROR_CONCEALMENT
+  EXPECT_EQ(VPX_CODEC_OK, vpx_codec_dec_init(&dec, &vpx_codec_vp8_dx_algo, NULL,
+                                             VPX_CODEC_USE_ERROR_CONCEALMENT));
+#else
+  EXPECT_EQ(VPX_CODEC_INCAPABLE,
+            vpx_codec_dec_init(&dec, &vpx_codec_vp8_dx_algo, NULL,
+                               VPX_CODEC_USE_ERROR_CONCEALMENT));
+#endif  // CONFIG_ERROR_CONCEALMENT
+}
+#endif  // CONFIG_VP8_DECODER
+
 #if CONFIG_VP9_DECODER
 // Test VP9 codec controls after a decode error to ensure the code doesn't
 // misbehave.