Web shell test to go back and forward.

ios/web/shell/test/utils/eg_util.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.
+
+#include "ios/web/shell/test/utils/eg_util.h"
+
+#import "ios/web/shell/view_controller.h"
+
+namespace earl_grey_util {
+
+CRWWebController* GetCurrentWebController() {
+  ViewController* vc = (ViewController*)[
+      [[[UIApplication sharedApplication] delegate] window] rootViewController];
+  DCHECK(vc);
+  CRWWebController* wc = [vc webController];
+  return wc;
+}
+
+}  // namespace earl_grey_util