Don't load WebUI if provisional navigation is for non-chrome URL

ios/web/webui/crw_web_ui_manager.mm

Index: ios/web/webui/crw_web_ui_manager.mm
diff --git a/ios/web/webui/crw_web_ui_manager.mm b/ios/web/webui/crw_web_ui_manager.mm
index 515dd2ec5340d985fbb59e27653702eb25d6bc87..0b74af1d7d3a6a80bc87467b654f48a41b281019 100644
--- a/ios/web/webui/crw_web_ui_manager.mm
+++ b/ios/web/webui/crw_web_ui_manager.mm
@@ -88,6 +88,10 @@ const char kScriptCommandPrefix[] = "webui";
 - (void)webState:(web::WebState*)webState
     didStartProvisionalNavigationForURL:(const GURL&)URL {
   DCHECK(webState == _webState);
+  // If URL is not an application specific URL, ignore the navigation.

[Eugene But (OOO till 7-30), 2015/11/23 17:31:42]

Do we have other app-specific URLs which are not WebUI? Do we need to account
for them as well?

+  if (!web::GetWebClient()->IsAppSpecificURL(URL))
+    return;
+
   GURL navigationURL(URL);
   // Add request group ID to the URL, if not present. Request group ID may
   // already be added if restoring state to a WebUI page.