webui/extensions: Get rid of usage of deprecated FromWStringHack() function.

chrome/browser/ui/webui/extensions/install_extension_handler.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/ui/webui/extensions/install_extension_handler.h"
 
 #include "base/bind.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/extensions/crx_installer.h"
@@ skipping 57 matching lines @@
     return;
   }
 
   if (drop_data->filenames.empty()) {
     DLOG(ERROR) << "Current drop data contains no files.";
     return;
   }
 
   const content::DropData::FileInfo& file_info = drop_data->filenames.front();
 
-  file_to_install_ = base::FilePath::FromWStringHack(
-      UTF16ToWide(file_info.path));
+  file_to_install_ = base::FilePath::FromUTF16Unsafe(file_info.path);
   // Use the display name if provided, for checking file names
   // (.path is likely a random hash value in that case).
   file_display_name_ =
       file_info.display_name.empty() ? file_info.path : file_info.display_name;
 }
 
 void InstallExtensionHandler::HandleStopDragMessage(const ListValue* args) {
   file_to_install_.clear();
   file_display_name_.clear();
 }
@@ skipping 37 matching lines @@
 void InstallExtensionHandler::HandleInstallDirectoryMessage(
     const ListValue* args) {
   Profile* profile = Profile::FromBrowserContext(
       web_ui()->GetWebContents()->GetBrowserContext());
   UnpackedInstaller::Create(
       ExtensionSystem::Get(profile)->
           extension_service())->Load(file_to_install_);
 }
 
 }  // namespace extensions