[ARC] Add browser test of ArcAuthService

chrome/browser/chromeos/arc/auth/arc_background_auth_code_fetcher.cc

Index: chrome/browser/chromeos/arc/auth/arc_background_auth_code_fetcher.cc
diff --git a/chrome/browser/chromeos/arc/auth/arc_background_auth_code_fetcher.cc b/chrome/browser/chromeos/arc/auth/arc_background_auth_code_fetcher.cc
index ed80b1540eebe03abd14cc93bcb5cff9b1c311fc..454a0ff2cfcb23eb4c66d9a73bfac1b51ecb22ec 100644
--- a/chrome/browser/chromeos/arc/auth/arc_background_auth_code_fetcher.cc
+++ b/chrome/browser/chromeos/arc/auth/arc_background_auth_code_fetcher.cc
@@ -12,12 +12,9 @@
 #include "base/json/json_writer.h"
 #include "base/logging.h"
 #include "base/values.h"
-#include "chrome/browser/signin/profile_oauth2_token_service_factory.h"
-#include "chrome/browser/signin/signin_manager_factory.h"
 #include "chrome/browser/ui/ash/multi_user/multi_user_util.h"
 #include "components/signin/core/account_id/account_id.h"
 #include "components/signin/core/browser/profile_oauth2_token_service.h"
-#include "components/signin/core/browser/signin_manager_base.h"
 #include "components/user_manager/known_user.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/common/url_constants.h"
@@ -42,11 +39,12 @@ constexpr char kLoginScopedToken[] = "login_scoped_token";
 constexpr char kGetAuthCodeHeaders[] =
     "Content-Type: application/json; charset=utf-8";
 constexpr char kContentTypeJSON[] = "application/json";
-constexpr char kEndPoint[] =
-    "https://www.googleapis.com/oauth2/v4/ExchangeToken";
 
 }  // namespace
 
+const char kAuthTokenExchangeEndPoint[] =
+    "https://www.googleapis.com/oauth2/v4/ExchangeToken";
+
 ArcBackgroundAuthCodeFetcher::ArcBackgroundAuthCodeFetcher(
     Profile* profile,
     ArcAuthContext* context)
@@ -102,8 +100,8 @@ void ArcBackgroundAuthCodeFetcher::OnGetTokenSuccess(
   std::string request_string;
   base::JSONWriter::Write(request_data, &request_string);
 
-  auth_code_fetcher_ =
-      net::URLFetcher::Create(0, GURL(kEndPoint), net::URLFetcher::POST, this);
+  auth_code_fetcher_ = net::URLFetcher::Create(
+      0, GURL(kAuthTokenExchangeEndPoint), net::URLFetcher::POST, this);
   auth_code_fetcher_->SetRequestContext(request_context_getter_);
   auth_code_fetcher_->SetUploadData(kContentTypeJSON, request_string);
   auth_code_fetcher_->SetLoadFlags(net::LOAD_DISABLE_CACHE |