Convert some GN test support targets to static libs.

components/safe_json/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.
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
 # GYP version: components/safe_json.gypi:safe_json
-source_set("safe_json") {
+static_library("safe_json") {
   sources = [
     "android/component_jni_registrar.cc",
     "android/component_jni_registrar.h",
     "json_sanitizer.cc",
     "json_sanitizer.h",
     "json_sanitizer_android.cc",
     "safe_json_parser.cc",
     "safe_json_parser.h",
     "safe_json_parser_android.cc",
     "safe_json_parser_android.h",
@@ skipping 34 matching lines @@
 
   deps = [
     ":safe_json",
     ":test_support",
     "//base",
     "//testing/gtest",
   ]
 }
 
 # GYP version: components/safe_json.gypi:safe_json_test_support
-source_set("test_support") {
+static_library("test_support") {
   testonly = true
   sources = [
     "testing_json_parser.cc",
     "testing_json_parser.h",
   ]
 
   deps = [
     ":safe_json",
     "//base",
   ]
 }