Revert "Fix a ton of compiler warnings."

chrome/browser/extensions/external_extension_provider.h

 // Copyright (c) 2009 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_EXTENSIONS_EXTERNAL_EXTENSION_PROVIDER_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTERNAL_EXTENSION_PROVIDER_H_
 
 #include <set>
 #include <string>
 
 #include "base/version.h"
 #include "chrome/common/extensions/extension.h"
 
 class FilePath;
 
 // This class is an abstract class for implementing external extensions
 // providers.
 class ExternalExtensionProvider {
  public:
   // ExternalExtensionProvider uses this interface to communicate back to the
   // caller what extensions are registered, and which |id|, |version| and |path|
   // they have. See also VisitRegisteredExtension below. Ownership of |version|
   // is not transferred to the visitor.
   class Visitor {
    public:
      virtual void OnExternalExtensionFound(const std::string& id,
                                            const Version* version,
                                            const FilePath& path,
                                            Extension::Location location) = 0;
-   protected:
-     ~Visitor() {}
   };
 
   virtual ~ExternalExtensionProvider() {}
 
   // Enumerate registered extension, calling OnExternalExtensionFound on
   // the |visitor| object for each registered extension found. |ids_to_ignore|
   // contains a list of extension ids that should not result in a call back.
   virtual void VisitRegisteredExtension(
       Visitor* visitor, const std::set<std::string>& ids_to_ignore) const = 0;
 
   // Gets the version of extension with |id| and its |location|. |location| can
   // be NULL. The caller is responsible for cleaning up the Version object
   // returned. This function returns NULL if the extension is not found.
   virtual Version* RegisteredVersion(const std::string& id,
                                      Extension::Location* location) const = 0;
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTERNAL_EXTENSION_PROVIDER_H_