[ios] Extracted web_test.h classes into separate files.

ios/web/test/web_test_with_web_controller.mm

+// Copyright 2016 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 "ios/web/test/web_test_with_web_controller.h"
+
+#import "ios/web/web_state/web_state_impl.h"
+
+namespace web {
+
+WebTestWithWebController::WebTestWithWebController() {}
+
+WebTestWithWebController::~WebTestWithWebController() {}
+
+CRWWebController* WebTestWithWebController::web_controller() {
+  return static_cast<web::WebStateImpl*>(web_state())->GetWebController();
+}
+
+}  // namespace web