Web shell test to go back and forward.

ios/web/shell/test/shell_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.
+
+#import <EarlGrey/EarlGrey.h>
+
+@interface GREYMatchers (WebShellAdditions)
+
+// Matcher for back button in web shell.
++ (id<GREYMatcher>)matcherForWebShellBackButton;
+
+// Matcher for forward button in web shell.
++ (id<GREYMatcher>)matcherForWebShellForwardButton;
+
+// Matcher for address field in web shell.
++ (id<GREYMatcher>)matcherForWebShellAddressField;
+
+@end
+
+#if !(GREY_DISABLE_SHORTHAND)
+
+extern "C" {
+// Shorthand for GREYMatchers::matcherForBackButton.
+id<GREYMatcher> shell_backButton();
+
+// Shorthand for GREYMatchers::matcherForForwardButton.
+id<GREYMatcher> shell_forwardButton();
+
+// Shorthand for GREYMatchers::matcherForAddressField.
+id<GREYMatcher> shell_addressField();
+}
+
+#endif