Create ChromeEarlGrey waitForWebViewContainingText.

ios/chrome/test/earl_grey/chrome_earl_grey.h

 // 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.
 
 #ifndef IOS_CHROME_TEST_EARL_GREY_CHROME_EARL_GREY_H_
 #define IOS_CHROME_TEST_EARL_GREY_CHROME_EARL_GREY_H_
 
 #import <EarlGrey/EarlGrey.h>
 
 #include "url/gurl.h"
@@ skipping 61 matching lines @@
 + (void)waitForStaticHTMLViewContainingText:(NSString*)text;
 
 // Waits for there to be no static html view, or a static html view that does
 // not contain |text|. If the condition is not met within a timeout, a
 // GREYAssert is induced.
 + (void)waitForStaticHTMLViewNotContainingText:(NSString*)text;
 
 // Waits for a Chrome error page. If it is not found within a timeout, a
 // GREYAssert is induced.
 + (void)waitForErrorPage;
+
+// Waits for the current web view to contain |text|. If the condition is not met
+// within a timeout, a GREYAssert is induced.
++ (void)waitForWebViewContainingText:(std::string)text;
 @end
 
 #endif  // IOS_CHROME_TEST_EARL_GREY_CHROME_EARL_GREY_H_