Convert BaseResponse to wrappers.BaseResponse (#3230)

Although the werkzeug changelog did not say so, it seem to have removed
certain symbols from `werkzeug`. We now use
`werkzeug.wrappers.BaseResponse` instead.

This is a cherry-pick of f833b39 to
avoid black reformatting.

Context:
https://werkzeug.palletsprojects.com/en/master/changes/#version-1-0-0

Author: stephanwlee

tensorboard/backend/empty_path_redirect_test.py

@@ -36,7 +36,7 @@ def setUp(self):
     app = empty_path_redirect.EmptyPathRedirectMiddleware(app)
     app = self._lax_strip_foo_middleware(app)
     self.app = app
-    self.server = werkzeug_test.Client(self.app, werkzeug.BaseResponse)
+    self.server = werkzeug_test.Client(self.app, werkzeug.wrappers.BaseResponse)
 
   def _lax_strip_foo_middleware(self, app):
     """Strips a `/foo` prefix if it exists; no-op otherwise."""

tensorboard/backend/experiment_id_test.py

@@ -33,7 +33,7 @@ class ExperimentIdMiddlewareTest(tb_test.TestCase):
   def setUp(self):
     super(ExperimentIdMiddlewareTest, self).setUp()
     self.app = experiment_id.ExperimentIdMiddleware(self._echo_app)
-    self.server = werkzeug_test.Client(self.app, werkzeug.BaseResponse)
+    self.server = werkzeug_test.Client(self.app, werkzeug.wrappers.BaseResponse)
 
   def _echo_app(self, environ, start_response):
     # https://www.python.org/dev/peps/pep-0333/#environ-variables

tensorboard/backend/path_prefix_test.py

@@ -63,7 +63,7 @@ def test_bad_path_prefix_with_trailing_slash(self):
 
   def test_empty_path_prefix(self):
     app = path_prefix.PathPrefixMiddleware(self._echo_app, "")
-    server = werkzeug_test.Client(app, werkzeug.BaseResponse)
+    server = werkzeug_test.Client(app, werkzeug.wrappers.BaseResponse)
 
     with self.subTest("at empty"):
       self._assert_ok(server.get(""), path="", script="")
@@ -77,7 +77,7 @@ def test_empty_path_prefix(self):
 
   def test_nonempty_path_prefix(self):
     app = path_prefix.PathPrefixMiddleware(self._echo_app, "/pfx")
-    server = werkzeug_test.Client(app, werkzeug.BaseResponse)
+    server = werkzeug_test.Client(app, werkzeug.wrappers.BaseResponse)
 
     with self.subTest("at root"):
       response = server.get("/pfx")
@@ -103,7 +103,7 @@ def test_composition(self):
     app = self._echo_app
     app = path_prefix.PathPrefixMiddleware(app, "/bar")
     app = path_prefix.PathPrefixMiddleware(app, "/foo")
-    server = werkzeug_test.Client(app, werkzeug.BaseResponse)
+    server = werkzeug_test.Client(app, werkzeug.wrappers.BaseResponse)
 
     response = server.get("/foo/bar/baz/quux")
     self._assert_ok(response, path="/baz/quux", script="/foo/bar")