[ios] Matcher for a generic interstitial page.

ios/web/public/test/earl_grey/web_view_matchers.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_WEB_PUBLIC_TEST_EARL_GREY_WEB_VIEW_MATCHERS_H_
 #define IOS_WEB_PUBLIC_TEST_EARL_GREY_WEB_VIEW_MATCHERS_H_
 
 #include <string>
 
 #import <EarlGrey/EarlGrey.h>
@@ skipping 19 matching lines @@
 id<GREYMatcher> webViewContainingBlockedImage(std::string image_id,
                                               CGSize expected_size,
                                               WebState* web_state);
 
 // Matcher for WKWebView containing an html element which matches |selector|.
 id<GREYMatcher> webViewCssSelector(std::string selector, WebState* web_state);
 
 // Matcher for WKWebView's scroll view.
 id<GREYMatcher> webViewScrollView(WebState* web_state);
 
-// Matcher for interstitial page containing |text|.
+// Matcher for an interstitial page. Does not wait if the page is not displayed.
+id<GREYMatcher> interstitial(WebState* web_state);
+
+// Matcher for interstitial page containing |text|. Waits until the text is
+// displayed or timed out.
 id<GREYMatcher> interstitialContainingText(NSString* text, WebState* web_state);
 
 }  // namespace web
 
 #endif  // IOS_WEB_PUBLIC_TEST_EARL_GREY_WEB_VIEW_MATCHERS_H_