[webui] Print out timeline link for full-screen trace viewing (#936)

* up

* update

python/ray/experimental/ui.py

@@ -448,8 +448,10 @@ def task_timeline():
 
         # Display the task trace within the Jupyter notebook
         clear_output(wait=True)
+        print(
+            "To view fullscreen, open chrome://tracing in Google Chrome "
+            "and load `{}`".format(json_tmp))
         display(IFrame(html_file_path, 900, 800))
-        print("Displaying {}".format(html_file_path))
 
     path_input.on_click(handle_submit)