Add a default Isolate gRPC proxy in config

appengine/swarming/proto/config.proto

 // 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.
 
 syntax = "proto2";
 
 
 // Schema for settings.cfg service config file in luci-config.
 message SettingsCfg {
   // id to inject into pages if applicable.
@@ skipping 34 matching lines @@
   // a task id can go.
   optional string display_server_url_template = 11;
 
   // Sets a maximum sleep time in seconds for bots that limits the exponental
   // backoff. If missing, the task scheduler will provide the default maximum
   // (usually 60s, but see bot_code/task_scheduler.py for details).
   optional int32 max_bot_sleep_time = 12;
 
   // Names of the authorization groups used by components/auth.
   optional AuthSettings auth = 13;
+
+  // Sets the default gRPC proxy for the bot's Isolate server calls.
+  optional string bot_isolate_grpc_proxy = 14;
 }
 
 
 // Configuration for swarming-isolate integration.
 message IsolateSettings {
   // URL of the default isolate server to use if it is not specified in a
   // task. Must start with "https://" or "http://",
   // e.g. "https://isolateserver.appspot.com"
   optional string default_server = 1;
 
@@ skipping 86 matching lines @@
 message AuthSettings {
   // Members of this group have full administrative access.
   optional string admins_group = 1;
   // Members of this group can fetch swarming bot code and bootstrap bots.
   optional string bot_bootstrap_group = 2;
   // Members of this group can schedule tasks and see everyone else's tasks.
   optional string privileged_users_group = 3;
   // Members of this group can schedule tasks and see only their own tasks.
   optional string users_group = 4;
 }