Fix various issues in RedirectToFileResourceHandler.

content/browser/loader/temporary_file_manager.h

+// Copyright 2013 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.
+
+#ifndef CONTENT_BROWSER_LOADER_TEMPORARY_FILE_MANAGER_H_
+#define CONTENT_BROWSER_LOADER_TEMPORARY_FILE_MANAGER_H_
+
+#include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "content/browser/loader/redirect_to_file_resource_handler.h"
+#include "content/public/browser/global_request_id.h"
+
+namespace content {
+
+// This class manages temporary files for RedirectToFileResourceHandler and the
+// ResourceDispatcherHost. It vends temporary files for resource requests and
+// arranges them to be readable by child processes. The TemporaryFileManager
+// retains references to each temporary on the child process's behalf. When both
+// the child process and the RedirectToFileResourceHandler have released the
+// file, it is deleted.
+class TemporaryFileManager : public TemporaryFileStreamFactory {
+ public:
+  TemporaryFileManager();
+  virtual ~TemporaryFileManager();
+
+  base::WeakPtr<TemporaryFileManager> AsWeakPtr() {
+    return weak_factory_.GetWeakPtr();
+  }
+
+  // Called when child process |child_id| has released the temporary attached to
+  // |request_id|.
+  void UnregisterDownloadedTempFile(int child_id, int request_id);
+
+  // Called when child process |child_id| dies. Releases all temporaries managed
+  // by the child.
+  void UnregisterFilesForChild(int child_id);
+
+  // TemporaryFileStreamFactory implementation:
+  virtual void CreateTemporary(
+      int child_id,
+      int request_id,
+      const TemporaryFileStreamFactory::Callback& callback) OVERRIDE;
+
+ private:
+  struct PendingTemporary;
+
+  void DidCreateTemporaryFile(PendingTemporary* pending,
+                              base::PlatformFileError error_code,
+                              base::PassPlatformFile file_handle,
+                              const base::FilePath& file_path);
+
+  void RegisterDownloadedTempFile(
+      int child_id,
+      int request_id,
+      webkit_blob::ShareableFileReference* reference);
+
+  // Collection of temp files downloaded for child processes via
+  // the download_to_file mechanism. We avoid deleting them until
+  // the client no longer needs them.
+  typedef std::map<int, scoped_refptr<webkit_blob::ShareableFileReference> >
+      DeletableFilesMap;  // key is request id
+  typedef std::map<int, DeletableFilesMap>
+      RegisteredTempFiles;  // key is child process id
+  RegisteredTempFiles registered_temp_files_;
+
+  // Collection of pending requests, to resolve races where
+  // UnregisterFilesForChild or UnregisterDownloadedTempFile are called while a
+  // CreateTemporary is in flight.

[mmenke, 2013/12/04 20:55:48]

optional:  May be worth noting that if we have yet to call CreateTemporary for a
RedirectRoFileResourceHandler, the request will be safely cancelled before it
has the chance to call into CreateTemporary.

[davidben, 2013/12/04 22:44:04]

Done. Also reordered DetachableResourceHandler and RedirectToFileResourceHandler
so that's actually true. :-) Not that you'll ever have download_to_file with a
resource type of PING or PREFETCH.

[mmenke, 2013/12/05 21:34:03]

I was actually thinking about the destroyed before it even starts to create a
file case...  I like your interpretation much better, though.

+  typedef std::map<GlobalRequestID, PendingTemporary*> PendingTemporaryMap;
+  PendingTemporaryMap pending_temporary_map_;
+
+  base::WeakPtrFactory<TemporaryFileManager> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(TemporaryFileManager);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_LOADER_TEMPORARY_FILE_MANAGER_H_