Convert test_support source sets to static libs

components/gcm_driver/crypto/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/crypto.gni")
 
 # GYP version: components/gcm_driver.gypi:gcm_driver_crypto
 source_set("crypto") {
   sources = [
     "encryption_header_parsers.cc",
@@ skipping 14 matching lines @@
     "//components/gcm_driver/crypto/proto",
     "//components/leveldb_proto",
     "//crypto",
     "//crypto:platform",
     "//net",
     "//third_party/protobuf:protobuf_lite",
   ]
 }
 
 # GYP version: components/gcm_driver.gypi:gcm_driver_crypto_test_support
-source_set("test_support") {
+static_library("test_support") {
   testonly = true
   sources = [
     "gcm_crypto_test_helpers.cc",
     "gcm_crypto_test_helpers.h",
   ]
 
   deps = [
     ":crypto",
     "//base",
     "//components/gcm_driver/common",
@@ skipping 16 matching lines @@
     "//base",
     "//base/test:test_support",
     "//components/gcm_driver/common",
     "//crypto",
     "//crypto:platform",
     "//net:test_support",
     "//testing/gtest",
     "//third_party/protobuf:protobuf_lite",
   ]
 }