Improve process launch handle sharing API.

content/public/browser/file_descriptor_info.h

-// 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.
-
-#ifndef CONTENT_PUBLIC_BROWSER_FILE_DESCRIPTOR_INFO_H_
-#define CONTENT_PUBLIC_BROWSER_FILE_DESCRIPTOR_INFO_H_
-
-#include <stddef.h>
-
-#include <memory>
-
-#include "base/files/file.h"
-#include "base/files/memory_mapped_file.h"
-#include "base/process/launch.h"
-
-namespace content {
-
-// FileDescriptorInfo is a collection of file descriptors which is needed to
-// launch a process. You should tell FileDescriptorInfo which FDs should be
-// closed and which shouldn't so that it can take care of the lifetime of FDs.
-//
-// See base/process/launcher.h for more details about launching a process.
-class FileDescriptorInfo {
- public:
-  virtual ~FileDescriptorInfo() {}
-
-  // Adds an FD associated with an ID, without delegating the ownerhip of ID.
-  virtual void Share(int id, base::PlatformFile fd) = 0;
-
-  // Similar to Share but also provides a region in that file that should be
-  // read in the launched process (accessible with GetRegionAt()).
-  virtual void ShareWithRegion(
-      int id,
-      base::PlatformFile fd,
-      const base::MemoryMappedFile::Region& region) = 0;
-
-  // Adds an FD associated with an ID, passing the FD ownership to
-  // FileDescriptorInfo.
-  virtual void Transfer(int id, base::ScopedFD fd) = 0;
-
-  // A vector backed map of registered ID-FD pairs.
-  virtual const base::FileHandleMappingVector& GetMapping() const = 0;
-
-  // A GetMapping() variant that adjusts the ID value by |delta|.
-  // Some environments need this trick.
-  virtual std::unique_ptr<base::FileHandleMappingVector>
-  GetMappingWithIDAdjustment(int delta) const = 0;
-
-  // API for iterating over the registered ID-FD pairs.
-  virtual base::PlatformFile GetFDAt(size_t i) const = 0;
-  virtual int GetIDAt(size_t i) const = 0;
-  virtual const base::MemoryMappedFile::Region& GetRegionAt(size_t i) const = 0;
-  virtual size_t GetMappingSize() const = 0;
-
-  // Returns true if |this| has ownership of |file|.
-  virtual bool OwnsFD(base::PlatformFile file) const = 0;
-  // Assuming |OwnsFD(file)|, releases the ownership.
-  virtual base::ScopedFD ReleaseFD(base::PlatformFile file) = 0;
-};
-
-}
-
-#endif  // CONTENT_PUBLIC_BROWSER_FILE_DESCRIPTOR_INFO_H_