[ios] EarlGrey test for scroll position restoration.

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

 // 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 "ios/web/public/test/earl_grey/web_view_matchers.h"
 
 #import <WebKit/WebKit.h>
 
 #include "base/mac/bind_objc_block.h"
 #include "base/strings/sys_string_conversions.h"
@@ skipping 10 matching lines @@
 }
 
 namespace web {
 
 id<GREYMatcher> webViewContainingText(const std::string& text,
                                       web::WebState* webState) {
   return
       [GREYMatchers matcherForWebViewContainingText:text inWebState:webState];
 }
 
+id<GREYMatcher> webViewScrollView(web::WebState* webState) {
+  return [GREYMatchers matcherForWebViewScrollViewInWebState:webState];
+}
+
 }  // namespace web
 
 @implementation GREYMatchers (WebViewAdditions)
 
 + (id<GREYMatcher>)matcherForWebViewContainingText:(const std::string&)text
                                         inWebState:(web::WebState*)webState {
   MatchesBlock matches = ^BOOL(UIView* view) {
     if (![view isKindOfClass:[WKWebView class]]) {
       return NO;
     }
@@ skipping 24 matching lines @@
   DescribeToBlock describe = ^(id<GREYDescription> description) {
     [description appendText:@"web view containing "];
     [description appendText:base::SysUTF8ToNSString(text)];
   };
 
   return [[[GREYElementMatcherBlock alloc] initWithMatchesBlock:matches
                                                descriptionBlock:describe]
       autorelease];
 }
 
++ (id<GREYMatcher>)matcherForWebViewScrollViewInWebState:
+    (web::WebState*)webState {
+  MatchesBlock matches = ^BOOL(UIView* view) {
+    return [view isKindOfClass:[UIScrollView class]] &&
+           [view.superview isKindOfClass:[WKWebView class]] &&
+           [view isDescendantOfView:webState->GetView()];
+  };
+
+  DescribeToBlock describe = ^(id<GREYDescription> description) {
+    [description appendText:@"web view scroll view"];
+  };
+
+  return [[[GREYElementMatcherBlock alloc] initWithMatchesBlock:matches
+                                               descriptionBlock:describe]
+      autorelease];
+}
+
 @end