Turn ArcSupportHost from Observer model to Delegate

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

Index: chrome/browser/chromeos/arc/auth/arc_manual_auth_code_fetcher.cc
diff --git a/chrome/browser/chromeos/arc/auth/arc_manual_auth_code_fetcher.cc b/chrome/browser/chromeos/arc/auth/arc_manual_auth_code_fetcher.cc
index 9b21352a72a9946112eacfbb96e5043e95b99e50..5a7d51b2e8160ba95e03d226e6282c918373bf02 100644
--- a/chrome/browser/chromeos/arc/auth/arc_manual_auth_code_fetcher.cc
+++ b/chrome/browser/chromeos/arc/auth/arc_manual_auth_code_fetcher.cc
@@ -17,11 +17,11 @@ ArcManualAuthCodeFetcher::ArcManualAuthCodeFetcher(ArcAuthContext* context,
     : context_(context), support_host_(support_host), weak_ptr_factory_(this) {
   DCHECK(context_);
   DCHECK(support_host_);
-  support_host_->AddObserver(this);
+  support_host_->SetAuthDelegate(this);
 }
 
 ArcManualAuthCodeFetcher::~ArcManualAuthCodeFetcher() {
-  support_host_->RemoveObserver(this);
+  support_host_->SetAuthDelegate(nullptr);
 }
 
 void ArcManualAuthCodeFetcher::Fetch(const FetchCallback& callback) {
@@ -61,7 +61,7 @@ void ArcManualAuthCodeFetcher::OnAuthFailed() {
   UpdateOptInCancelUMA(OptInCancelReason::NETWORK_ERROR);
 }
 
-void ArcManualAuthCodeFetcher::OnRetryClicked() {
+void ArcManualAuthCodeFetcher::OnAuthRetryClicked() {
   DCHECK(!pending_callback_.is_null());
   FetchInternal();
 }