Shorten audio_modem test_support target to just "test_support".

components/audio_modem/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.
 
 static_library("audio_modem") {
   sources = [
     "audio_modem_switches.cc",
     "audio_modem_switches.h",
     "audio_player.h",
     "audio_player_impl.cc",
@@ skipping 10 matching lines @@
   ]
 
   deps = [
     "//base",
     "//content",
     "//media",
     "//third_party/webrtc/common_audio",
   ]
 }
 
-static_library("audio_modem_test_support") {
+source_set("test_support") {
   sources = [
     "test/random_samples.cc",
     "test/random_samples.h",
     "test/stub_modem.cc",
     "test/stub_modem.h",
     "test/stub_whispernet_client.cc",
     "test/stub_whispernet_client.h",
   ]
 
   deps = [
     "//base",
     "//media",
   ]
 }