[ARC] Add browser test of ArcAuthService

chrome/browser/chromeos/arc/arc_auth_context.cc

 // Copyright 2016 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/chromeos/arc/arc_auth_context.h"
 
 #include "base/callback_helpers.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/chromeos/arc/arc_support_host.h"
@@ skipping 76 matching lines @@
 
 void ArcAuthContext::OnRefreshTokenTimeout() {
   LOG(WARNING) << "Failed to wait for refresh token.";
   token_service_->RemoveObserver(this);
   base::ResetAndReturn(&callback_).Run(nullptr);
 }
 
 void ArcAuthContext::StartFetchers() {
   DCHECK(!refresh_token_timeout_.IsRunning());
   ResetFetchers();
+
+  if (skip_merge_session_for_testing_) {
+    OnMergeSessionSuccess("");
+    return;
+  }
+
   ubertoken_fetcher_.reset(
       new UbertokenFetcher(token_service_, this, GaiaConstants::kChromeOSSource,
                            storage_partition_->GetURLRequestContext()));
   ubertoken_fetcher_->StartFetchingToken(account_id_);
 }
 
 void ArcAuthContext::OnUbertokenSuccess(const std::string& token) {
   ResetFetchers();
   merger_fetcher_.reset(
       new GaiaAuthFetcher(this, GaiaConstants::kChromeOSSource,
@@ skipping 20 matching lines @@
   ResetFetchers();
   base::ResetAndReturn(&callback_).Run(nullptr);
 }
 
 void ArcAuthContext::ResetFetchers() {
   merger_fetcher_.reset();
   ubertoken_fetcher_.reset();
 }
 
 }  // namespace arc