Move gn _run target generation into test().

tools/battor_agent/BUILD.gn

 # Copyright 2015 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("//testing/test.gni")
 
 # Works only on desktop platforms.
 assert(is_win || is_linux || is_mac)
 
 executable("battor_agent") {
@@ skipping 41 matching lines @@
     "//base",
     "//base/test:run_all_unittests",
     "//base/test:test_support",
     "//device/serial",
     "//device/serial:test_support",
     "//mojo/public/c/system:for_shared_library",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }
-
-# TODO(GYP): Delete this after we've converted everything to GN.
-# The _run targets exist only for compatibility w/ GYP.
-group("battor_agent_unittests_run") {
-  testonly = true
-  deps = [
-    ":battor_agent_unittests",
-  ]
-}