Convert test_support source sets to static libs

components/browser_sync/browser/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("//build/config/features.gni")
 
 source_set("browser") {
   sources = [
     "profile_sync_components_factory_impl.cc",
     "profile_sync_components_factory_impl.h",
@@ skipping 79 matching lines @@
     "//components/webdata_services:test_support",
     "//google_apis",
     "//net",
     "//sync:test_support_sync_internal_api",
     "//testing/gmock",
     "//testing/gtest",
     "//ui/base",
   ]
 }
 
-source_set("test_support") {
+static_library("test_support") {
   testonly = true
   sources = [
     "abstract_profile_sync_service_test.cc",
     "abstract_profile_sync_service_test.h",
     "profile_sync_service_mock.cc",
     "profile_sync_service_mock.h",
     "profile_sync_test_util.cc",
     "profile_sync_test_util.h",
     "test_http_bridge_factory.cc",
     "test_http_bridge_factory.h",
@@ skipping 16 matching lines @@
     "//components/sync_driver:test_support",
     "//components/sync_sessions:test_support",
     "//components/syncable_prefs:test_support",
     "//google_apis",
     "//net:test_support",
     "//sync:test_support_sync_core",
     "//sync:test_support_sync_internal_api",
     "//testing/gmock",
   ]
 }