Fix handling of external protocols with PlzNavigate.

chrome/common/chrome_content_client.cc

 // Copyright (c) 2012 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.
 
 #include "chrome/common/chrome_content_client.h"
 
 #include <stdint.h>
 
 #include <map>
 #include <memory>
@@ skipping 575 matching lines @@
 
   // Treat as secure because communication with them is entirely in the browser,
   // so there is no danger of manipulation or eavesdropping on communication
   // with them by third parties.
   schemes->secure_schemes.push_back(extensions::kExtensionScheme);
 
   schemes->secure_origins = GetSecureOriginWhitelist();
 
   schemes->no_access_schemes.push_back(chrome::kChromeNativeScheme);
 
+  // chrome-native: is a scheme used for placeholder navigations that allow
+  // UIs to be drawn with platform native widgets instead of HTML.  These pages
+  // should be treated as empty documents that can commit synchronously.
+  schemes->empty_document_schemes.push_back(chrome::kChromeNativeScheme);
+
 #if BUILDFLAG(ENABLE_EXTENSIONS)
   if (extensions::feature_util::ExtensionServiceWorkersEnabled())
     schemes->service_worker_schemes.push_back(extensions::kExtensionScheme);
 
   // As far as Blink is concerned, they should be allowed to receive CORS
   // requests. At the Extensions layer, requests will actually be blocked unless
   // overridden by the web_accessible_resources manifest key.
   // TODO(kalman): See what happens with a service worker.
   schemes->cors_enabled_schemes.push_back(extensions::kExtensionScheme);
 
@@ skipping 87 matching lines @@
   if (!origin_trial_policy_)
     origin_trial_policy_ = base::MakeUnique<ChromeOriginTrialPolicy>();
   return origin_trial_policy_.get();
 }
 
 #if defined(OS_ANDROID)
 media::MediaClientAndroid* ChromeContentClient::GetMediaClientAndroid() {
   return new ChromeMediaClientAndroid();
 }
 #endif  // OS_ANDROID