Fixes document type detection on iOS 9.

ios/web/web_state/ui/crw_wk_web_view_web_controller.mm

Index: ios/web/web_state/ui/crw_wk_web_view_web_controller.mm
diff --git a/ios/web/web_state/ui/crw_wk_web_view_web_controller.mm b/ios/web/web_state/ui/crw_wk_web_view_web_controller.mm
index a254291c0b210d52bbffc4e7411cfdcf15a22b97..fa5719fa087ddc55a9da86deb62dabf60d4bdb0e 100644
--- a/ios/web/web_state/ui/crw_wk_web_view_web_controller.mm
+++ b/ios/web/web_state/ui/crw_wk_web_view_web_controller.mm
@@ -510,16 +510,7 @@ WKWebViewErrorSource WKWebViewErrorSourceFromError(NSError* error) {
   }
 
   std::string mimeType = self.webState->GetContentsMimeType();

[Eugene But (OOO till 7-30), 2015/11/20 18:13:49]

Optional NIT: Could you please s/mimeType/MIMEType :)

I originally wrote this code with incorrect name :(

[stkhapugin, 2015/11/23 13:35:48]

Done.

-  if (mimeType.empty()) {
-    return web::WEB_VIEW_DOCUMENT_TYPE_UNKNOWN;
-  }
-
-  if (mimeType == "text/html" || mimeType == "application/xhtml+xml" ||
-      mimeType == "application/xml") {
-    return web::WEB_VIEW_DOCUMENT_TYPE_HTML;
-  }
-
-  return web::WEB_VIEW_DOCUMENT_TYPE_GENERIC;
+  return [self documentTypeFromMIMEType:base::SysUTF8ToNSString(mimeType)];
 }
 
 - (void)loadRequest:(NSMutableURLRequest*)request {