Mark gtest and gmock as testonly in GN.

components/invalidation/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.
 
 static_library("invalidation") {
   sources = [
     "ack_handle.cc",
     "ack_handle.h",
     "ack_handler.cc",
     "ack_handler.h",
@@ skipping 75 matching lines @@
     "//jingle:notifier",
     "//third_party/cacheinvalidation",
 
     # TODO(sync): Remove this (http://crbug.com/133352);
     "//third_party/protobuf:protobuf_lite",
     # "//third_party/cacheinvalidation/src/google/cacheinvalidation:cacheinvalidation_proto_cpp",
   ]
 }
 
 static_library("test_support") {
+  testonly = true
   sources = [
     "fake_invalidation_handler.cc",
     "fake_invalidation_handler.h",
     "fake_invalidation_state_tracker.cc",
     "fake_invalidation_state_tracker.h",
     "fake_invalidator.cc",
     "fake_invalidator.h",
     "invalidation_service_test_template.cc",
     "invalidation_service_test_template.h",
     "invalidation_test_util.cc",
@@ skipping 21 matching lines @@
     "//jingle:notifier_test_util",
     "//net",
     "//testing/gmock",
     "//third_party/cacheinvalidation",
 
     # TODO(sync): Remove this (http://crbug.com/133352);
     "//third_party/protobuf:protobuf_lite",
     # "//third_party/cacheinvalidation/src/google/cacheinvalidation:cacheinvalidation_proto_cpp",
   ]
 }