[ios] EarlGrey test for scroll position restoration.

ios/web/public/test/earl_grey/web_view_matchers.h

Index: ios/web/public/test/earl_grey/web_view_matchers.h
diff --git a/ios/web/public/test/earl_grey/web_view_matchers.h b/ios/web/public/test/earl_grey/web_view_matchers.h
index 9f52db501d10db4127dfd1d101745744eea470a5..1206dda3a4073b57c7e2015cbe1b5f0cab40e782 100644
--- a/ios/web/public/test/earl_grey/web_view_matchers.h
+++ b/ios/web/public/test/earl_grey/web_view_matchers.h
@@ -14,6 +14,9 @@ namespace web {
 id<GREYMatcher> webViewContainingText(const std::string& text,
                                       web::WebState* webState);
 
+// Shorthand for GREYMatchers::matcherForWebViewScrollViewInWebState.
+id<GREYMatcher> webViewScrollView(web::WebState* webState);
+
 }  // namespace web
 
 @interface GREYMatchers (WebViewAdditions)
@@ -22,4 +25,8 @@ id<GREYMatcher> webViewContainingText(const std::string& text,
 + (id<GREYMatcher>)matcherForWebViewContainingText:(const std::string&)text
                                         inWebState:(web::WebState*)webState;
 
+// Matcher for WKWebView's scroll view.
++ (id<GREYMatcher>)matcherForWebViewScrollViewInWebState:
+    (web::WebState*)webState;
+
 @end