Create ChromeEarlGrey waitForWebViewContainingText.

ios/web/public/test/web_view_content_test_util.h

+// 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.
+
+#ifndef IOS_WEB_PUBLIC_TEST_WEB_VIEW_CONTENT_TEST_UTIL_H_
+#define IOS_WEB_PUBLIC_TEST_WEB_VIEW_CONTENT_TEST_UTIL_H_
+
+#import "ios/web/public/web_state/web_state.h"
+
+namespace web {
+namespace test {
+
+// Returns true if there is a web view for |web_state| that contains |text|.
+// Otherwise, returns false.
+bool IsWebViewContainingText(web::WebState* web_state, const std::string& text);
+
+}  // namespace test
+}  // namespace web
+
+#endif  // IOS_WEB_PUBLIC_TEST_WEB_VIEW_CONTENT_TEST_UTIL_H_