RefCounted types should not have public destructors, delegate cleanup

chrome/common/net/gaia/oauth2_mint_token_flow.h

 // Copyright (c) 2012 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_COMMON_NET_GAIA_OAUTH2_MINT_TOKEN_FLOW_H_
 #define CHROME_COMMON_NET_GAIA_OAUTH2_MINT_TOKEN_FLOW_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 70 matching lines @@
 
     std::string login_refresh_token;
     std::string extension_id;
     std::string client_id;
     std::vector<std::string> scopes;
     Mode mode;
   };
 
   class Delegate {
    public:
-    Delegate() {}
-    virtual ~Delegate() {}
     virtual void OnMintTokenSuccess(const std::string& access_token) {}
     virtual void OnIssueAdviceSuccess(const IssueAdviceInfo& issue_advice)  {}
     virtual void OnMintTokenFailure(const GoogleServiceAuthError& error) {}
+
+   protected:
+    virtual ~Delegate() {}
   };
 
   // An interceptor for tests.
   class InterceptorForTests {
    public:
     // Returns true if the success callback should be called and false for
     // failures.
     virtual bool DoIntercept(const OAuth2MintTokenFlow* flow,
                              std::string* access_token,
                              GoogleServiceAuthError* error) = 0;
@@ skipping 40 matching lines @@
       const base::DictionaryValue* dict, std::string* access_token);
 
   net::URLRequestContextGetter* context_;
   Delegate* delegate_;
   Parameters parameters_;
 
   DISALLOW_COPY_AND_ASSIGN(OAuth2MintTokenFlow);
 };
 
 #endif  // CHROME_COMMON_NET_GAIA_OAUTH2_MINT_TOKEN_FLOW_H_