Moves nghttp2_session_callbacks creation from test code to nghttp2_callbacks.h.

PiperOrigin-RevId: 368278257
Change-Id: Ib27ad77919145292256c4cd0150e20c335084ab3
diff --git a/http2/adapter/nghttp2_callbacks.cc b/http2/adapter/nghttp2_callbacks.cc
index e897fa8..b54c915 100644
--- a/http2/adapter/nghttp2_callbacks.cc
+++ b/http2/adapter/nghttp2_callbacks.cc
@@ -14,6 +14,7 @@
 
 namespace http2 {
 namespace adapter {
+namespace callbacks {
 
 int OnBeginFrame(nghttp2_session* /* session */,
                  const nghttp2_frame_hd* header,
@@ -187,5 +188,24 @@
   return bytes_to_send;
 }
 
+nghttp2_session_callbacks* Create() {
+  nghttp2_session_callbacks* callbacks;
+  nghttp2_session_callbacks_new(&callbacks);
+
+  nghttp2_session_callbacks_set_on_begin_frame_callback(callbacks,
+                                                        &OnBeginFrame);
+  nghttp2_session_callbacks_set_on_frame_recv_callback(callbacks,
+                                                       &OnFrameReceived);
+  nghttp2_session_callbacks_set_on_begin_headers_callback(callbacks,
+                                                          &OnBeginHeaders);
+  nghttp2_session_callbacks_set_on_header_callback2(callbacks, &OnHeader);
+  nghttp2_session_callbacks_set_on_data_chunk_recv_callback(callbacks,
+                                                            &OnDataChunk);
+  nghttp2_session_callbacks_set_on_stream_close_callback(callbacks,
+                                                         &OnStreamClosed);
+  return callbacks;
+}
+
+}  // namespace callbacks
 }  // namespace adapter
 }  // namespace http2