Convert some GN test support targets to static libs.

components/printing/test/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.
 
-source_set("test_support") {
+static_library("test_support") {
   testonly = true
 
   sources = [
     "mock_printer.cc",
     "mock_printer.h",
     "print_mock_render_thread.cc",
     "print_mock_render_thread.h",
     "print_test_content_renderer_client.cc",
     "print_test_content_renderer_client.h",
   ]
 
   public_deps = [
     "//base",
     "//components/printing/common",
     "//components/printing/renderer",
     "//content/public/common",
     "//content/public/renderer",
     "//content/test:test_support",
     "//ipc",
     "//printing",
     "//skia",
     "//testing/gtest",
     "//ui/gfx/geometry",
   ]
 }