Convert test_support source sets to static libs

chrome/browser/media/router/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("//mojo/public/tools/bindings/mojom.gni")
 import("//testing/test.gni")
 
 static_library("router") {
   deps = [
@@ skipping 65 matching lines @@
     ]
   }
 }
 
 mojom("mojo_bindings") {
   sources = [
     "mojo/media_router.mojom",
   ]
 }
 
-source_set("test_support") {
+static_library("test_support") {
   testonly = true
   deps = [
     ":router",
     "//chrome/test:test_support",
     "//testing/gmock",
   ]
   sources = [
     "mock_media_router.cc",
     "mock_media_router.h",
     "mock_screen_availability_listener.cc",
     "mock_screen_availability_listener.h",
     "test_helper.cc",
     "test_helper.h",
   ]
 
   if (!is_android) {
     deps += [
       ":mojo_bindings",
       "//extensions/common",
     ]
     sources += [
       "mojo/media_router_mojo_test.cc",
       "mojo/media_router_mojo_test.h",
     ]
   }
 }