Fixed some PHP errors
diff --git a/src/php/ext/grpc/call_credentials.c b/src/php/ext/grpc/call_credentials.c
index 8bf5120..a395d53 100644
--- a/src/php/ext/grpc/call_credentials.c
+++ b/src/php/ext/grpc/call_credentials.c
@@ -35,6 +35,7 @@
#include <grpc/grpc.h>
#include <grpc/grpc_security.h>
+#include <grpc/support/string_util.h>
zend_class_entry *grpc_ce_call_credentials;
#if PHP_MAJOR_VERSION >= 7
diff --git a/src/php/ext/grpc/call_credentials.h b/src/php/ext/grpc/call_credentials.h
index 9be8763..663cc68 100755
--- a/src/php/ext/grpc/call_credentials.h
+++ b/src/php/ext/grpc/call_credentials.h
@@ -65,9 +65,12 @@
} plugin_state;
/* Callback function for plugin creds API */
-void plugin_get_metadata(void *state, grpc_auth_metadata_context context,
- grpc_credentials_plugin_metadata_cb cb,
- void *user_data);
+int plugin_get_metadata(
+ void *ptr, grpc_auth_metadata_context context,
+ grpc_credentials_plugin_metadata_cb cb, void *user_data,
+ grpc_metadata creds_md[GRPC_METADATA_CREDENTIALS_PLUGIN_SYNC_MAX],
+ size_t *num_creds_md, grpc_status_code *status,
+ const char **error_details);
/* Cleanup function for plugin creds API */
void plugin_destroy_state(void *ptr);