Replace the DownloadFileManager with direct ownership of DownloadFileImpl

content/browser/renderer_host/resource_dispatcher_host_impl.cc

Index: content/browser/renderer_host/resource_dispatcher_host_impl.cc
diff --git a/content/browser/renderer_host/resource_dispatcher_host_impl.cc b/content/browser/renderer_host/resource_dispatcher_host_impl.cc
index 5b1121599dd3f982cf24e54d89ce51386a0ff884..894ac63232eb3095fc67b329e0780c9b144f7a06 100644
--- a/content/browser/renderer_host/resource_dispatcher_host_impl.cc
+++ b/content/browser/renderer_host/resource_dispatcher_host_impl.cc
@@ -25,7 +25,6 @@
 #include "content/browser/cert_store_impl.h"
 #include "content/browser/child_process_security_policy_impl.h"
 #include "content/browser/cross_site_request_manager.h"
-#include "content/browser/download/download_file_manager.h"
 #include "content/browser/download/download_resource_handler.h"
 #include "content/browser/download/save_file_manager.h"
 #include "content/browser/download/save_file_resource_handler.h"
@@ -351,8 +350,7 @@ ResourceDispatcherHost* ResourceDispatcherHost::Get() {
 }
 
 ResourceDispatcherHostImpl::ResourceDispatcherHostImpl()
-    : download_file_manager_(new DownloadFileManager(NULL)),
-      save_file_manager_(new SaveFileManager()),
+    : save_file_manager_(new SaveFileManager()),
       request_id_(-1),
       is_shutdown_(false),
       max_outstanding_requests_cost_per_process_(