[CRD iOS] Refactor an interface for RemotingAuthorization

remoting/ios/app/main.mm

 // Copyright 2017 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.
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 #import <UIKit/UIKit.h>
 
 #include "base/at_exit.h"
 #include "base/command_line.h"
 #include "base/i18n/icu_util.h"
 #import "remoting/ios/app/app_delegate.h"
+#import "remoting/ios/facade/remoting_oauth_authentication.h"
+#import "remoting/ios/facade/remoting_service.h"
 
 int main(int argc, char* argv[]) {
   // This class is designed to fulfill the dependents needs when it goes out of
   // scope and gets destructed.
   base::AtExitManager exitManager;
 
   // Publicize the CommandLine.
   base::CommandLine::Init(argc, argv);
 
   // Required to find the ICU data file, used by some file_util routines.
   base::i18n::InitializeICU();
 
 #ifdef DEBUG
   // Set min log level for debug builds.  For some reason this has to be
   // negative.
   logging::SetMinLogLevel(-1);
 #endif
 
   @autoreleasepool {
+    RemotingService.instance.authentication =
+        [[RemotingOAuthAuthentication alloc] init];
     return UIApplicationMain(
         argc, argv, nil, NSStringFromClass([AppDelegate class]));
   }
 }