Add a default Isolate gRPC proxy in config

appengine/swarming/swarming_bot/bot_code/remote_client.py

 # Copyright 2016 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 import base64
 import logging
 import threading
 import time
 import traceback
 import urllib
@@ skipping 23 matching lines @@
 # time). On GCE machines it is usually 5 min.
 AUTH_HEADERS_EXPIRATION_SEC = 4*60+30
 
 
 # How long to wait for a response from the server. Must not be greater than
 # AUTH_HEADERS_EXPIRATION_SEC, since otherwise there's a chance auth headers
 # will expire while we wait for connection.
 NET_CONNECTION_TIMEOUT_SEC = 3*60
 
 
-def createRemoteClient(server, auth, useGrpc):
-  if useGrpc:
+def createRemoteClient(server, auth, grpc_proxy):
+  if grpc_proxy:
     import remote_client_grpc
-    return remote_client_grpc.RemoteClientGrpc(server)
+    return remote_client_grpc.RemoteClientGrpc(grpc_proxy)
   return RemoteClientNative(server, auth)
 
 
 class RemoteClientNative(object):
   """RemoteClientNative knows how to make authenticated calls to the backend.
 
   It also holds in-memory cache of authentication headers and periodically
   refreshes them (by calling supplied callback, that usually is implemented in
   terms of bot_config.get_authentication_headers() function).
 
@@ skipping 255 matching lines @@
         'account_id': account_id,
         'id': bot_id,
         'scopes': scopes,
         'task_id': task_id,
     })
     if not resp:
       raise InternalError('Error when minting the token')
     if resp.get('error'):
       raise MintOAuthTokenError(resp['error'])
     return resp