Split up ios/web:test_support.

ios/web/public/test/BUILD.gn

+# Copyright 2017 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.
+
+source_set("test") {
+  testonly = true
+
+  deps = [
+    "//base",
+    "//base/test:test_support",
+    "//ios/testing:ios_test_support",
+    "//ios/third_party/gcdwebserver",
+    "//ios/web:web",
+    "//ios/web:web_arc",
+    "//ios/web/public/test/fakes",
+    "//ios/web/public/test/http_server",
+    "//ios/web/test:test_support",
+    "//testing/gtest",
+    "//ui/base",
+    "//url",
+  ]
+
+  allow_circular_includes_from = [ "//ios/web/test:test_support" ]
+
+  sources = [
+    "js_test_util.h",
+    "js_test_util.mm",
+    "native_controller_test_util.h",
+    "native_controller_test_util.mm",
+    "navigation_test_util.h",
+    "navigation_test_util.mm",
+    "scoped_testing_web_client.h",
+    "scoped_testing_web_client.mm",
+    "test_redirect_observer.h",
+    "test_redirect_observer.mm",
+    "test_web_thread.h",
+    "test_web_thread_bundle.h",
+    "url_test_util.h",
+    "web_js_test.h",
+    "web_test.h",
+    "web_test.mm",
+    "web_test_suite.h",
+    "web_test_with_web_state.h",
+    "web_test_with_web_state.mm",
+    "web_view_interaction_test_util.h",
+    "web_view_interaction_test_util.mm",
+  ]
+}