Make an error message verbose to investigate a un-reproducible bug....

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 23 matching lines @@
 
 // The file to write our decoded images to, relative to the extension_path.
 const char kDecodedImagesFilename[] = "DECODED_IMAGES";
 
 // The file to write our decoded message catalogs to, relative to the
 // extension_path.
 const char kDecodedMessageCatalogsFilename[] = "DECODED_MESSAGE_CATALOGS";
 
 // Errors
 const char* kCouldNotCreateDirectoryError =
-    "Could not create directory for unzipping.";
+    "Could not create directory for unzipping: ";
 const char* kCouldNotDecodeImageError = "Could not decode theme image.";
 const char* kCouldNotUnzipExtension = "Could not unzip extension.";
 const char* kPathNamesMustBeAbsoluteOrLocalError =
     "Path names must not be absolute or contain '..'.";
 
 // A limit to stop us passing dangerously large canvases to the browser.
 const int kMaxImageCanvas = 4096 * 4096;
 
 }  // namespace
 
@@ skipping 88 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(kTempExtensionName);
   if (!file_util::CreateDirectory(temp_install_dir_)) {
-    SetError(kCouldNotCreateDirectoryError);
+#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;
   }
 
   if (!Unzip(extension_path_, temp_install_dir_)) {
     SetError(kCouldNotUnzipExtension);
     return false;
   }
 
   // Parse the manifest.
   parsed_manifest_.reset(ReadManifest());
@@ 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;
 }