Fix and refactor downloaded file handling in the loading stack

content/browser/loader/resource_dispatcher_host_impl.cc

Index: content/browser/loader/resource_dispatcher_host_impl.cc
diff --git a/content/browser/loader/resource_dispatcher_host_impl.cc b/content/browser/loader/resource_dispatcher_host_impl.cc
index 4117eae4cdc25ff63a0a9027ed0d186bd863423c..6a9619422de8541e9279d139c0e0ee671f2676fd 100644
--- a/content/browser/loader/resource_dispatcher_host_impl.cc
+++ b/content/browser/loader/resource_dispatcher_host_impl.cc
@@ -45,6 +45,7 @@
 #include "content/browser/loader/async_resource_handler.h"
 #include "content/browser/loader/async_revalidation_manager.h"
 #include "content/browser/loader/detachable_resource_handler.h"
+#include "content/browser/loader/downloaded_temp_file_impl.h"
 #include "content/browser/loader/intercepting_resource_handler.h"
 #include "content/browser/loader/loader_delegate.h"
 #include "content/browser/loader/mime_sniffing_resource_handler.h"
@@ -1769,12 +1770,13 @@ void ResourceDispatcherHostImpl::OnDidChangePriority(
 }
 
 void ResourceDispatcherHostImpl::RegisterDownloadedTempFile(
-    int child_id, int request_id, const base::FilePath& file_path) {
-  scoped_refptr<ShareableFileReference> reference =
-      ShareableFileReference::Get(file_path);
-  DCHECK(reference.get());
+    std::unique_ptr<DownloadedTempFileImpl> downloaded_file) {

[mmenke, 2016/11/17 16:59:33]

Do we even need to change all this?  Would it be better to just make
DownloadedTempFileImpl call
ChildProcessSecurityPolicyImpl::GetInstance()->GrantReadFile itself, and rely on
the connection_error_handler to ensure teardown (Or just let the Mojo object in
the other process own it directly), and leave the old code alone?  Then when we
switch over to mojo, we can remove all this stuff from the RDH as well.

[tzik, 2016/11/22 13:54:45]

OK, let me take the second: Let the Mojo object in the other process own it.

+  int child_id = downloaded_file->child_id();
+  int request_id = downloaded_file->request_id();
+  scoped_refptr<storage::ShareableFileReference> reference =

[dcheng, 2016/11/17 11:16:02]

Are lines 1774-1776 still needed?

[tzik, 2016/11/22 13:54:45]

Reverted.

+      downloaded_file->reference();
 
-  registered_temp_files_[child_id][request_id] = reference;
+  registered_temp_files_[child_id][request_id] = std::move(downloaded_file);
   ChildProcessSecurityPolicyImpl::GetInstance()->GrantReadFile(
       child_id, reference->path());