Convert test_support source sets to static libs

base/test/BUILD.gn

 # Copyright (c) 2013 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/ui.gni")
 import("//build/config/nacl/config.gni")
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
-source_set("test_config") {
+static_library("test_config") {
   testonly = true
   sources = [
     "test_switches.cc",
     "test_switches.h",
     "test_timeouts.cc",
     "test_timeouts.h",
   ]
   deps = [
     "//base",
   ]
 }
 
 # GYP: //base/base.gyp:test_support_base
-source_set("test_support") {
+static_library("test_support") {
   testonly = true
   sources = [
     "gtest_util.cc",
     "gtest_util.h",
     "gtest_xml_unittest_result_printer.cc",
     "gtest_xml_unittest_result_printer.h",
     "gtest_xml_util.cc",
     "gtest_xml_util.h",
     "histogram_tester.cc",
     "histogram_tester.h",
@@ skipping 172 matching lines @@
       "//third_party/icu:icuuc",
       "//third_party/libxml",
     ]
   }
 }
 
 config("perf_test_config") {
   defines = [ "PERF_TEST" ]
 }
 
+# This is a source set instead of a static library because it seems like some
+# linkers get confused when "main" is in a static library, and if you link to
+# this, you always want the object file anyway.
 source_set("test_support_perf") {
   testonly = true
   sources = [
     "run_all_perftests.cc",
   ]
   deps = [
     ":test_support",
     "//base",
     "//testing/gtest",
   ]
 
   public_configs = [ ":perf_test_config" ]
 }
 
-source_set("test_launcher_nacl_nonsfi") {
+static_library("test_launcher_nacl_nonsfi") {
   testonly = true
   sources = [
     "launcher/test_launcher_nacl_nonsfi.cc",
     "launcher/test_launcher_nacl_nonsfi.h",
   ]
   deps = [
     ":test_support",
   ]
 }
 
-source_set("run_all_unittests") {
+static_library("run_all_unittests") {
   testonly = true
   sources = [
     "run_all_unittests.cc",
   ]
   deps = [
     ":test_support",
   ]
 }
 
 if (is_linux) {
@@ skipping 11 matching lines @@
 
 if (is_android) {
   generate_jni("base_unittests_jni_headers") {
     sources = [
       "android/java/src/org/chromium/base/ContentUriTestUtils.java",
       "android/java/src/org/chromium/base/TestUiThread.java",
     ]
     jni_package = "base"
   }
 }