layers: Refactor CmdCopyBuffer for pre-post style

Change-Id: Ic0004cad00ba04295e8c05a703a085e07d3ad56e
diff --git a/layers/buffer_validation.h b/layers/buffer_validation.h
index 6c2398b..8116f3b 100644
--- a/layers/buffer_validation.h
+++ b/layers/buffer_validation.h
@@ -171,4 +171,10 @@
 void PreCallRecordCmdCopyImage(layer_data *device_data, GLOBAL_CB_NODE *cb_node, IMAGE_STATE *src_image_state,
                                IMAGE_STATE *dst_image_state);
 
+bool PreCallValidateCmdCopyBuffer(layer_data *device_data, GLOBAL_CB_NODE *cb_node, BUFFER_STATE *src_buffer_state,
+                                  BUFFER_STATE *dst_buffer_state);
+
+void PreCallRecordCmdCopyBuffer(layer_data *device_data, GLOBAL_CB_NODE *cb_node, BUFFER_STATE *src_buffer_state,
+                                BUFFER_STATE *dst_buffer_state);
+
 #endif  // CORE_VALIDATION_BUFFER_VALIDATION_H_