Mark gtest and gmock as testonly in GN.

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")
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
 source_set("test_support") {
-  testonly = true
+  # TODO http://crbug.com/412064 enable this flag all the time.
+  testonly = !is_component_build
   sources = [
     "expectations/expectation.cc",
     "expectations/expectation.h",
     "expectations/parser.cc",
     "expectations/parser.h",
     "gtest_xml_util.cc",
     "gtest_xml_util.h",
     "histogram_tester.cc",
     "histogram_tester.h",
     "launcher/test_launcher.cc",
@@ skipping 136 matching lines @@
 }
 
 if (is_android) {
   generate_jni("base_unittests_jni_headers") {
     sources = [
       "android/java/src/org/chromium/base/ContentUriTestUtils.java",
     ]
     jni_package = "base"
   }
 }