Web shell test to go back and forward.

ios/web/shell/test/utils/web_view_egutil.h

Index: ios/web/shell/test/utils/web_view_egutil.h
diff --git a/ios/web/shell/test/utils/web_view_egutil.h b/ios/web/shell/test/utils/web_view_egutil.h
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index 0000000000000000000000000000000000000000..c505f56569c6a7504699fb17b97c7f8e80275ebc
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+++ b/ios/web/shell/test/utils/web_view_egutil.h
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+// 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 WKWebView containing |text|.
++ (id<GREYMatcher>)matcherForWebViewContainingText:(NSString*)text;
+
+#if !(GREY_DISABLE_SHORTHAND)
+
+// Shorthand for GREYMatchers::matcherForWebViewContainingText
+GREY_EXPORT id<GREYMatcher> shell_webViewContainingText(NSString* text);
+#endif
+
+@end