Turn ArcSupportHost from Observer model to Delegate

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

 // 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.
 
 #ifndef CHROME_BROWSER_CHROMEOS_ARC_AUTH_ARC_MANUAL_AUTH_CODE_FETCHER_H_
 #define CHROME_BROWSER_CHROMEOS_ARC_AUTH_ARC_MANUAL_AUTH_CODE_FETCHER_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "chrome/browser/chromeos/arc/arc_support_host.h"
 #include "chrome/browser/chromeos/arc/auth/arc_auth_code_fetcher.h"
 
 namespace net {
 class URLRequestContextGetter;
 }
 
 namespace arc {
 
 class ArcAuthContext;
 
 // Implements the auth token fetching procedure with user's "SIGN IN" button
 // click.
 class ArcManualAuthCodeFetcher : public ArcAuthCodeFetcher,
-                                 public ArcSupportHost::Observer {
+                                 public ArcSupportHost::AuthDelegate {
  public:
   ArcManualAuthCodeFetcher(ArcAuthContext* context,
                            ArcSupportHost* support_host);
   ~ArcManualAuthCodeFetcher() override;
 
   // ArcAuthCodeFetcher:
   void Fetch(const FetchCallback& callback) override;
 
  private:
   void FetchInternal();
 
   // Called when HTTP request gets ready.
   void OnContextPrepared(net::URLRequestContextGetter* request_context_getter);
 
-  // ArcSupportHost::Observer:
+  // ArcSupportHost::AuthDelegate:
   void OnAuthSucceeded(const std::string& auth_code) override;
   void OnAuthFailed() override;
-  void OnRetryClicked() override;
+  void OnAuthRetryClicked() override;
 
   ArcAuthContext* const context_;
   ArcSupportHost* const support_host_;
 
   FetchCallback pending_callback_;
 
   base::WeakPtrFactory<ArcManualAuthCodeFetcher> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ArcManualAuthCodeFetcher);
 };
 
 }  // namespace arc
 
 #endif  // CHROME_BROWSER_CHROMEOS_ARC_AUTH_ARC_MANUAL_AUTH_CODE_FETCHER_H_