Reland 'Convert //net and //chromecast to std::unordered_*'

net/base/platform_mime_util_linux.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 "net/base/platform_mime_util.h"
 
 #include <string>
 
 #include "base/logging.h"
 #include "build/build_config.h"
@@ skipping 84 matching lines @@
   // If we wanted to do this properly, we would read the mime.cache file which
   // has a section where they assign a glob (*.gif) to a mimetype
   // (image/gif). We look up the "heaviest" glob for a certain mime type and
   // then then try to chop off "*.".
 
   return false;
 }
 
 void PlatformMimeUtil::GetPlatformExtensionsForMimeType(
     const std::string& mime_type,
-    base::hash_set<base::FilePath::StringType>* extensions) const {
+    std::unordered_set<base::FilePath::StringType>* extensions) const {
   base::FilePath::StringType ext;
   if (GetPreferredExtensionForMimeType(mime_type, &ext))
     extensions->insert(ext);
 }
 
 }  // namespace net