Fix few compilation errors on Windows in media/ during Windows GN build.

media/cast/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.
 
 component("cast") {
   deps = [
     ":sender",
     ":receiver",
   ]
 }
@@ skipping 182 matching lines @@
   if (is_ios) {
     deps += [ "//media:media_for_cast_ios" ]
     deps -= [
       "//media",
       "//third_party/libvpx",
       "//third_party/opus",
     ]
   }
 }
 
-source_set("test_support") {
+static_library("test_support") {
   testonly = true
   sources = [
     # TODO(hclam): FFmpeg.
     #    "test/fake_media_source.cc",
     #    "test/fake_media_source.h",
     "test/fake_single_thread_task_runner.cc",
     "test/fake_single_thread_task_runner.h",
     "test/skewed_single_thread_task_runner.cc",
     "test/skewed_single_thread_task_runner.h",
     "test/skewed_tick_clock.cc",
@@ skipping 150 matching lines @@
   sources = [
     "test/utility/udp_proxy_main.cc",
   ]
 
   deps = [
     ":test_support",
     "//base",
     "//net",
   ]
 }