arc: Prepare ArcAuthEndpoint flag for finch experiment.

chrome/browser/chromeos/arc/arc_auth_code_fetcher.h

Index: chrome/browser/chromeos/arc/arc_auth_code_fetcher.h
diff --git a/chrome/browser/chromeos/arc/arc_auth_code_fetcher.h b/chrome/browser/chromeos/arc/arc_auth_code_fetcher.h
index c514602e32540424672c3683ad89c62d32e0827a..33ae5c26140b2329e0fa5637e3f8608ee099ffa6 100644
--- a/chrome/browser/chromeos/arc/arc_auth_code_fetcher.h
+++ b/chrome/browser/chromeos/arc/arc_auth_code_fetcher.h
@@ -28,8 +28,7 @@ class ArcAuthCodeFetcher : public OAuth2TokenService::Consumer,
  public:
   ArcAuthCodeFetcher(ArcAuthCodeFetcherDelegate* delegate,
                      net::URLRequestContextGetter* request_context_getter,
-                     Profile* profile,
-                     const std::string& auth_endpoint);
+                     Profile* profile);
   ~ArcAuthCodeFetcher() override;
 
   // OAuth2TokenService::Consumer:
@@ -50,9 +49,6 @@ class ArcAuthCodeFetcher : public OAuth2TokenService::Consumer,
   net::URLRequestContextGetter* const request_context_getter_;
   Profile* const profile_;
 
-  // URL to request auth code.
-  const std::string auth_endpoint_;
-
   std::unique_ptr<OAuth2TokenService::Request> login_token_request_;
   std::unique_ptr<net::URLFetcher> auth_code_fetcher_;