Generate all extension schema namespaces as "api" and instead vary the generated bundle names.

extensions/shell/common/api/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/json_schema_api.gni")
 import("schemas.gni")
 
 # GYP version: extensions/shell/common/api/api.gyp:shell_api
 json_schema_api("api") {
   schemas = true
   bundle = true
+  bundle_name = "Shell"
 }
 
 # GYP version: extensions/shell/browser/api/api_registration.gyp:shell_api_registration
 json_schema_api("api_registration") {
   impl_dir = "//extensions/shell/browser/api"
   bundle_registration = true
+  bundle_name = "Shell"
 
   deps = [
     ":api",
   ]
 }