Disable external navigation for file downloads.

chrome/browser/android/chrome_feature_list.cc

 // 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.
 
 #include "chrome/browser/android/chrome_feature_list.h"
 
 #include <stddef.h>
 
 #include <string>
 
@@ skipping 19 matching lines @@
     &features::kCredentialManagementAPI,
     &features::kSimplifiedFullscreenUI,
     &kImportantSitesInCBD,
     &kMediaStyleNotification,
     &kNTPFakeOmniboxTextFeature,
     &kNTPMaterialDesign,
     &kNTPOfflinePagesFeature,
     &kNTPSnippetsFeature,
     &kNTPToolbarFeature,
     &kPhysicalWebFeature,
+    &kSystemDownloadManager,
     &offline_pages::kOfflinePagesBackgroundLoadingFeature,
 };
 
 }  // namespace
 
 const base::Feature kImportantSitesInCBD{"ImportantSitesInCBD",
                                          base::FEATURE_DISABLED_BY_DEFAULT};
 
 const base::Feature kMediaStyleNotification {
   "MediaStyleNotification", base::FEATURE_ENABLED_BY_DEFAULT
@@ skipping 38 matching lines @@
   NOTREACHED();
   return false;
 }
 
 bool RegisterChromeFeatureListJni(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 }  // namespace android
 }  // namespace chrome