Convert some GN test support targets to static libs.

components/sync_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.
 
 import("//build/buildflag_header.gni")
 import("//build/config/features.gni")
 
-source_set("sync_driver") {
+static_library("sync_driver") {
   sources = [
     "about_sync_util.cc",
     "about_sync_util.h",
     "backend_data_type_configurer.cc",
     "backend_data_type_configurer.h",
     "backend_migrator.cc",
     "backend_migrator.h",
     "change_processor.cc",
     "change_processor.h",
     "data_type_controller.cc",
@@ skipping 130 matching lines @@
       "sync_policy_handler.cc",
       "sync_policy_handler.h",
     ]
     deps += [
       "//components/policy",
       "//components/policy:policy_component",
     ]
   }
 }
 
-source_set("test_support") {
+static_library("test_support") {
   testonly = true
   sources = [
     "change_processor_mock.cc",
     "change_processor_mock.h",
     "data_type_controller_mock.cc",
     "data_type_controller_mock.h",
     "data_type_manager_mock.cc",
     "data_type_manager_mock.h",
     "fake_data_type_controller.cc",
     "fake_data_type_controller.h",
@@ skipping 86 matching lines @@
   ]
 
   if (enable_configuration_policy) {
     sources += [ "sync_policy_handler_unittest.cc" ]
     deps += [
       "//components/policy",
       "//components/policy:policy_component",
     ]
   }
 }