[ARC] Add browser test of ArcAuthService

chrome/browser/chromeos/arc/arc_auth_context.cc

Index: chrome/browser/chromeos/arc/arc_auth_context.cc
diff --git a/chrome/browser/chromeos/arc/arc_auth_context.cc b/chrome/browser/chromeos/arc/arc_auth_context.cc
index 99d78b3e6723b584ed0d6a8b4920df17935194b2..2f33e559f45c23be95d1e56f81ca9a173bd2da83 100644
--- a/chrome/browser/chromeos/arc/arc_auth_context.cc
+++ b/chrome/browser/chromeos/arc/arc_auth_context.cc
@@ -94,6 +94,12 @@ void ArcAuthContext::OnRefreshTokenTimeout() {
 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()));