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

ios/web/webui/crw_web_ui_manager.mm

 // Copyright 2015 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/webui/crw_web_ui_manager.h"
 
 #include "base/mac/bind_objc_block.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/memory/scoped_vector.h"
 #import "base/strings/sys_string_conversions.h"
@@ skipping 70 matching lines @@
 - (void)dealloc {
   [self resetWebState];
   [super dealloc];
 }
 
 #pragma mark - CRWWebStateObserver Methods
 
 - (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.
   GURL requestURL =
       web::ExtractRequestGroupIDFromURL(net::NSURLWithGURL(URL))
           ? URL
           : net::GURLWithNSURL(web::AddRequestGroupIDToURL(
                 net::NSURLWithGURL(URL), _webState->GetRequestGroupID()));
   base::WeakNSObject<CRWWebUIManager> weakSelf(self);
   [self loadWebUIPageForURL:requestURL
@@ skipping 103 matching lines @@
 
 - (scoped_ptr<web::URLFetcherBlockAdapter>)
         fetcherForURL:(const GURL&)URL
     completionHandler:(web::URLFetcherBlockAdapterCompletion)handler {
   return scoped_ptr<web::URLFetcherBlockAdapter>(
       new web::URLFetcherBlockAdapter(
           URL, _webState->GetBrowserState()->GetRequestContext(), handler));
 }
 
 @end