Add the "virtual" keyword on method overrides that are missing it.

chrome/browser/extensions/sandboxed_extension_unpacker.h

 // Copyright (c) 2010 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_SANDBOXED_EXTENSION_UNPACKER_H_
 #define CHROME_BROWSER_EXTENSIONS_SANDBOXED_EXTENSION_UNPACKER_H_
 #pragma once
 
 #include <string>
 
@@ skipping 104 matching lines @@
   // put here because we cannot run windows crypto code in the sandbox. But we
   // could still have this method statically on ExtensionUnpacker so that code
   // just for unpacking is there and code just for sandboxing of unpacking is
   // here.
   bool ValidateSignature();
 
   // Starts the utility process that unpacks our extension.
   void StartProcessOnIOThread(const FilePath& temp_crx_path);
 
   // SandboxedExtensionUnpacker
-  void OnUnpackExtensionSucceeded(const DictionaryValue& manifest);
-  void OnUnpackExtensionFailed(const std::string& error_message);
-  void OnProcessCrashed();
+  virtual void OnUnpackExtensionSucceeded(const DictionaryValue& manifest);
+  virtual void OnUnpackExtensionFailed(const std::string& error_message);
+  virtual void OnProcessCrashed();
 
   void ReportFailure(const std::string& message);
   void ReportSuccess();
 
   // Overwrites original manifest with safe result from utility process.
   // Returns NULL on error. Caller owns the returned object.
   DictionaryValue* RewriteManifestFile(const DictionaryValue& manifest);
 
   // Overwrites original files with safe results from utility process.
   // Reports error and returns false if it fails.
@@ skipping 25 matching lines @@
   scoped_refptr<Extension> extension_;
 
   // Whether we've received a response from the utility process yet.
   bool got_response_;
 
   // The public key that was extracted from the CRX header.
   std::string public_key_;
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_SANDBOXED_EXTENSION_UNPACKER_H_