Make --allow-cross-domain-auth-prompt equivalent to a preference.

chrome/browser/browser_process_impl.cc

Index: chrome/browser/browser_process_impl.cc
===================================================================
--- chrome/browser/browser_process_impl.cc	(revision 85807)
+++ chrome/browser/browser_process_impl.cc	(working copy)
@@ -647,6 +647,10 @@
   return *plugin_finder_disabled_pref_;
 }
 
+bool BrowserProcessImpl::allow_cross_origin_auth_prompt() const {
+  return *allow_cross_origin_auth_prompt_pref_;
+}
+
 void BrowserProcessImpl::Observe(NotificationType type,
                                  const NotificationSource& source,
                                  const NotificationDetails& details) {
@@ -919,6 +923,12 @@
                                    local_state_.get(), NULL);
   plugin_finder_disabled_pref_.MoveToThread(BrowserThread::IO);
 
+  // The cross origin auth prompt preference is only neeed on the IO thread.
+  local_state_->RegisterBooleanPref(prefs::kAllowCrossOriginAuthPrompt, false);
+  allow_cross_origin_auth_prompt_pref_.Init(
+      prefs::kAllowCrossOriginAuthPrompt, local_state_.get(), NULL);
+  allow_cross_origin_auth_prompt_pref_.MoveToThread(BrowserThread::IO);
+
   // This is observed by ChildProcessSecurityPolicy, which lives in content/
   // though, so it can't register itself.
   local_state_->RegisterListPref(prefs::kDisabledSchemes);