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

content/public/test/test_download_request_handler.cc

Index: content/public/test/test_download_request_handler.cc
diff --git a/content/public/test/test_download_request_handler.cc b/content/public/test/test_download_request_handler.cc
index e1d15b1a22dbba379d5a48e94f807421a6b36bb7..add301064ccabb8a71a3edbeee8fc66e13f81843 100644
--- a/content/public/test/test_download_request_handler.cc
+++ b/content/public/test/test_download_request_handler.cc
@@ -498,7 +498,8 @@ TestDownloadRequestHandler::Interceptor::Register(
 
 void TestDownloadRequestHandler::Interceptor::Unregister() {
   net::URLRequestFilter* filter = net::URLRequestFilter::GetInstance();
-  filter->RemoveUrlHandler(url_);
+  GURL url = url_;  // Make a copy as |this| will be deleted.
+  filter->RemoveUrlHandler(url);
   // We are deleted now since the filter owned |this|.
 }