Fix a bug where packing an extension with bad private key causes crash.

chrome/browser/extensions/extension_creator.cc

 // 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.
 
 #include "chrome/browser/extensions/extension_creator.h"
 
 #include <string>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 210 matching lines @@
   while ((bytes_read = fread(buffer.get(), 1, buffer_size,
        zip_handle.get())) > 0) {
     if (!signature_creator->Update(buffer.get(), bytes_read)) {
       error_message_ =
           l10n_util::GetStringUTF8(IDS_EXTENSION_ERROR_WHILE_SIGNING);
       return false;
     }
   }
   zip_handle.Close();
 
-  signature_creator->Final(signature);
+  if (!signature_creator->Final(signature)) {
+    error_message_ =
+        l10n_util::GetStringUTF8(IDS_EXTENSION_ERROR_WHILE_SIGNING);
+    return false;
+  }
   return true;
 }
 
 bool ExtensionCreator::WriteCRX(const base::FilePath& zip_path,
                                 crypto::RSAPrivateKey* private_key,
                                 const std::vector<uint8>& signature,
                                 const base::FilePath& crx_path) {
   if (base::PathExists(crx_path))
     base::DeleteFile(crx_path, false);
   ScopedStdioHandle crx_handle(file_util::OpenFile(crx_path, "wb"));
@@ skipping 78 matching lines @@
       SignZip(zip_path, key_pair.get(), &signature) &&
       WriteCRX(zip_path, key_pair.get(), signature, crx_path)) {
     result = true;
   }
 
   base::DeleteFile(zip_path, false);
   return result;
 }
 
 }  // namespace extensions