expose passthrough for WebSocketHandler.get_compression_options

adds `NotebookApp.websocket_compression_options` configurable,
with a default of None (no compression)

notebook/base/zmqhandlers.py

@@ -296,5 +296,4 @@ class AuthenticatedZMQStreamHandler(ZMQStreamHandler, IPythonHandler):
         self.session = Session(config=self.config)
 
     def get_compression_options(self):
-        # use deflate compress websocket
-        return {}
+        return self.settings.get('websocket_compression_options', None)

notebook/notebookapp.py

@@ -93,7 +93,7 @@ from jupyter_client.kernelspec import KernelSpecManager, NoSuchKernel, NATIVE_KE
 from jupyter_client.session import Session
 from nbformat.sign import NotebookNotary
 from traitlets import (
-    Dict, Unicode, Integer, List, Bool, Bytes, Instance,
+    Any, Dict, Unicode, Integer, List, Bool, Bytes, Instance,
     TraitError, Type, Float, observe, default, validate
 )
 from ipython_genutils import py3compat
@@ -740,7 +740,18 @@ class NotebookApp(JupyterApp):
     tornado_settings = Dict(config=True,
             help="Supply overrides for the tornado.web.Application that the "
                  "Jupyter notebook uses.")
-    
+
+    websocket_compression_options = Any(None, config=True,
+        help="""
+        Set the tornado compression options for websocket connections.
+
+        This value will be returned from :meth:`WebSocketHandler.get_compression_options`.
+        None (default) will disable compression.
+        A dict (even an empty one) will enable compression.
+
+        See the tornado docs for WebSocketHandler.get_compression_options for details.
+        """
+    )
     terminado_settings = Dict(config=True,
             help='Supply overrides for terminado. Currently only supports "shell_command".')
 
@@ -1107,6 +1118,7 @@ class NotebookApp(JupyterApp):
     def init_webapp(self):
         """initialize tornado webapp and httpserver"""
         self.tornado_settings['allow_origin'] = self.allow_origin
+        self.tornado_settings['websocket_compression_options'] = self.websocket_compression_options
         if self.allow_origin_pat:
             self.tornado_settings['allow_origin_pat'] = re.compile(self.allow_origin_pat)
         self.tornado_settings['allow_credentials'] = self.allow_credentials