[ios] EarlGrey test for PDF Mime type.

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 9ced53e9d0005ffa934ef35503e754aafb427f6f..efa073b566b577a1536f34ac94fa1a603f26d8ae 100644
--- a/ios/web/public/test/earl_grey/web_view_matchers.h
+++ b/ios/web/public/test/earl_grey/web_view_matchers.h
@@ -10,6 +10,9 @@
 
 namespace web {
 
+// Shorthand for GREYMatchers::matcherForWebViewInWebState.
+id<GREYMatcher> webViewInWebState(web::WebState* webState);
+
 // Shorthand for GREYMatchers::matcherForWebViewContainingText:inWebState.
 id<GREYMatcher> webViewContainingText(const std::string& text,
                                       web::WebState* webState);
@@ -25,6 +28,9 @@ id<GREYMatcher> webViewScrollView(web::WebState* webState);
 
 @interface GREYMatchers (WebViewAdditions)
 
+// Matcher for WKWebView which belogs to the given |webState|.
++ (id<GREYMatcher>)matcherForWebViewInWebState:(web::WebState*)webState;
+
 // Matcher for WKWebView containing |text|.
 + (id<GREYMatcher>)matcherForWebViewContainingText:(const std::string&)text
                                         inWebState:(web::WebState*)webState;