[ios] EarlGrey test for PDF Mime type.

ios/web/shell/test/earl_grey/shell_matchers.h

Index: ios/web/shell/test/earl_grey/shell_matchers.h
diff --git a/ios/web/shell/test/earl_grey/shell_matchers.h b/ios/web/shell/test/earl_grey/shell_matchers.h
index 3158c9a196f75fb8f6c042e081157577b0503795..93cb1905257d21240aabd0562fe7daf78211d5b8 100644
--- a/ios/web/shell/test/earl_grey/shell_matchers.h
+++ b/ios/web/shell/test/earl_grey/shell_matchers.h
@@ -17,6 +17,9 @@ id<GREYMatcher> webViewCssSelector(const std::string& selector);
 // Shorthand for GREYMatchers::matcherForWebViewScrollView.
 id<GREYMatcher> webViewScrollView();
 
+// Shorthand for GREYMatchers::matcherForWebViewMIMETYPE.
+id<GREYMatcher> webViewMimeType(const std::string& mime_type);
+
 // Shorthand for GREYMatchers::matcherForAddressFieldEqualToText.
 id<GREYMatcher> addressFieldText(const std::string& text);
 
@@ -42,6 +45,9 @@ id<GREYMatcher> addressField();
 // Matcher for WKWebView's scroll view.
 + (id<GREYMatcher>)matcherForWebViewScrollView;
 
+// Matcher for WKWebView with given MIME type.
++ (id<GREYMatcher>)matcherForWebViewMIMEType:(const std::string&)MIMEType;
+
 // Matcher for web shell address field text property equal to |text|.
 + (id<GREYMatcher>)matcherForAddressFieldEqualToText:(const std::string&)text;