If CreateDirectory() fails during extension unpacking, log the exact OS call that failed.

chrome/common/extensions/extension_unpacker.cc

 // 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.
 
 #include "chrome/common/extensions/extension_unpacker.h"
 
 #include "base/file_util.h"
 #include "base/scoped_handle.h"
 #include "base/scoped_temp_dir.h"
 #include "base/string_util.h"
@@ skipping 122 matching lines @@
 
   return true;
 }
 
 bool ExtensionUnpacker::Run() {
   LOG(INFO) << "Installing extension " << extension_path_.value();
 
   // <profile>/Extensions/INSTALL_TEMP/<version>
   temp_install_dir_ =
     extension_path_.DirName().AppendASCII(filenames::kTempExtensionName);
+
+#if defined(OS_WIN)
+  std::ostringstream log_stream;
+  std::string dir_string = WideToUTF8(temp_install_dir_.value());
+  log_stream << kCouldNotCreateDirectoryError << dir_string << std::endl;
+  if (!file_util::CreateDirectoryExtraLogging(temp_install_dir_, log_stream)) {
+    log_stream.flush();
+    SetError(log_stream.str());
+    return false;
+  }
+#else
   if (!file_util::CreateDirectory(temp_install_dir_)) {
-#if defined(OS_WIN)
-    std::string dir_string = WideToUTF8(temp_install_dir_.value());
-#else
     std::string dir_string = temp_install_dir_.value();
-#endif
     SetError(kCouldNotCreateDirectoryError + dir_string);
     return false;
   }
+#endif
 
   if (!Unzip(extension_path_, temp_install_dir_)) {
     SetError(kCouldNotUnzipExtension);
     return false;
   }
 
   // Parse the manifest.
   parsed_manifest_.reset(ReadManifest());
   if (!parsed_manifest_.get())
     return false;  // Error was already reported.
@@ skipping 132 matching lines @@
 
   parsed_catalogs_->Set(relative_path.DirName().ToWStringHack(),
                         root.release());
 
   return true;
 }
 
 void ExtensionUnpacker::SetError(const std::string &error) {
   error_message_ = error;
 }