Convert test_support source sets to static libs

components/gcm_driver/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.
 
 # GYP version: components/gcm_driver.gypi:gcm_driver
 static_library("gcm_driver") {
   sources = [
     "android/component_jni_registrar.cc",
     "android/component_jni_registrar.h",
     "default_gcm_app_handler.cc",
@@ skipping 89 matching lines @@
       "gcm_driver_desktop.h",
       "gcm_stats_recorder_impl.cc",
       "gcm_stats_recorder_impl.h",
     ]
     deps -= [ "//google_apis/gcm" ]
     deps += [ "android:jni_headers" ]
   }
 }
 
 # GYP version: components/gcm_driver.gypi:gcm_driver_test_support
-source_set("test_support") {
+static_library("test_support") {
   testonly = true
   sources = [
     "fake_gcm_app_handler.cc",
     "fake_gcm_app_handler.h",
     "fake_gcm_client.cc",
     "fake_gcm_client.h",
     "fake_gcm_client_factory.cc",
     "fake_gcm_client_factory.h",
     "fake_gcm_driver.cc",
     "fake_gcm_driver.h",
@@ skipping 52 matching lines @@
   if (is_android) {
     sources -= [
       "gcm_account_mapper_unittest.cc",
       "gcm_channel_status_request_unittest.cc",
       "gcm_client_impl_unittest.cc",
       "gcm_driver_desktop_unittest.cc",
       "gcm_stats_recorder_impl_unittest.cc",
     ]
   }
 }