Fixes the interactive default browser UX for policy setting

chrome/browser/browser_process_impl.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/browser/browser_process_impl.h"
 
 #include <stddef.h>
 #include <algorithm>
 #include <map>
 #include <utility>
@@ skipping 1178 matching lines @@
       content::BrowserThread::GetMessageLoopProxyForThread(
           content::BrowserThread::UI),
       content::BrowserThread::GetMessageLoopProxyForThread(
           content::BrowserThread::IO),
       blocking_task_runner);
 #endif  // defined(OS_ANDROID)
 }
 
 void BrowserProcessImpl::ApplyDefaultBrowserPolicy() {
   if (local_state()->GetBoolean(prefs::kDefaultBrowserSettingEnabled)) {
+    // The worker pointer is reference counted. While it is running, the
+    // message loops of the FILE and UI thread will hold references to it
+    // and it will be automatically freed once all its tasks have finished.
     scoped_refptr<shell_integration::DefaultWebClientWorker>
-        set_browser_worker = new shell_integration::DefaultBrowserWorker(NULL);
+        set_browser_worker = new shell_integration::DefaultBrowserWorker(
+            nullptr,
+            /*delete_observer=*/false);
+    // The user interaction must always be disabled when applying the default
+    // browser policy since it is done at each browser startup and the result
+    // of the interaction cannot be forced.
+    set_browser_worker->set_interactive_permitted(false);
     set_browser_worker->StartSetAsDefault();
   }
 }
 
 void BrowserProcessImpl::ApplyAllowCrossOriginAuthPromptPolicy() {
   bool value = local_state()->GetBoolean(prefs::kAllowCrossOriginAuthPrompt);
   ResourceDispatcherHost::Get()->SetAllowCrossOriginAuthPrompt(value);
 }
 
 void BrowserProcessImpl::ApplyMetricsReportingPolicy() {
@@ skipping 71 matching lines @@
 }
 
 void BrowserProcessImpl::OnAutoupdateTimer() {
   if (CanAutorestartForUpdate()) {
     DLOG(WARNING) << "Detected update.  Restarting browser.";
     RestartBackgroundInstance();
   }
 }
 
 #endif  // (defined(OS_WIN) || defined(OS_LINUX)) && !defined(OS_CHROMEOS)