Files required by a service now listed in manifest.

base/file_descriptor_store.h

+// Copyright 2017 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 BASE_FILE_DESCRIPTOR_STORE_H_
+#define BASE_FILE_DESCRIPTOR_STORE_H_
+
+#include <stdint.h>
+
+#include <vector>
+

[Ken Rockot(use gerrit already), 2017/02/09 17:17:27]

include <string>

[Jay Civelli, 2017/02/09 22:08:26]

Done.

+#include "base/files/memory_mapped_file.h"
+#include "base/memory/singleton.h"
+
+namespace base {
+
+// The file descriptor store is used to associate file descriptors with keys
+// that must be unique.
+// It is used to share file descriptors from a process to its child.
+class BASE_EXPORT FileDescriptorStore {
+ public:
+  struct Descriptor {
+    Descriptor(const std::string& key, int fd);
+    Descriptor(const std::string& key,
+               int fd,
+               base::MemoryMappedFile::Region region);
+
+    // Globally unique key.
+    std::string key;
+    // Actual FD.
+    int fd;

[Ken Rockot(use gerrit already), 2017/02/09 17:17:27]

nit: Use ScopedFD? You will have to define a move ctor and operator=, or use a
unique_ptr<Descriptor> in Mapping, but it either way it's much safer. I'm not so
much worried about leaks here as I am worried about double-closing, which seems
to be a popular mistake to make.

[Jay Civelli, 2017/02/09 22:08:27]

Great idea, now using a ScopedFD.

+    // Optional region, defaults to kWholeFile.
+    base::MemoryMappedFile::Region region;
+  };
+  typedef std::vector<Descriptor> Mapping;

[Ken Rockot(use gerrit already), 2017/02/09 17:17:27]

Why not a map<std::string, Descriptor> and remove "key" from Descriptor?

Also please use "using" syntax instead of typedef.

[Jay Civelli, 2017/02/09 22:08:27]

Done.
I copied this file over from GlobalDescriptor without much thoughts.
It's much cleaner now, thanks!

+
+  // Returns the singleton instance of FileDescriptorStore.
+  static FileDescriptorStore* GetInstance();
+
+  // Gets a descriptor given a key. It is a fatal error if the key is not known.
+  int Get(const std::string& key) const;

[Ken Rockot(use gerrit already), 2017/02/09 17:17:27]

Get = TakeFD, and make it return a ScopedFD?

[Jay Civelli, 2017/02/09 22:08:27]

Done.

+
+  // Gets a descriptor given a key. Returns -1 on error.
+  int MaybeGet(const std::string& key) const;

[Ken Rockot(use gerrit already), 2017/02/09 17:17:27]

MaybeTakeFD?

[Jay Civelli, 2017/02/09 22:08:27]

Done.

+
+  // Gets a region given a key. It is a fatal error if the key is not known.
+  base::MemoryMappedFile::Region GetRegion(const std::string& key) const;
+
+  // Sets the descriptor for the given |key|. This sets the region associated
+  // with |key| to kWholeFile.
+  void Set(const std::string& key, int fd);

[Ken Rockot(use gerrit already), 2017/02/09 17:17:28]

ScopedFD

[Jay Civelli, 2017/02/09 22:08:26]

Done.

+
+  // Sets the descriptor and |region| for the given |key|.
+  void Set(const std::string& key,

[Ken Rockot(use gerrit already), 2017/02/09 17:17:28]

ScopedFD

[Jay Civelli, 2017/02/09 22:08:26]

Done.

+           int fd,
+           base::MemoryMappedFile::Region region);
+
+  void Reset(const Mapping& mapping);

[Ken Rockot(use gerrit already), 2017/02/09 17:17:27]

If making the above changes, this should just become Mapping and can be moved at
the call site. Alternatively, if as a matter of convenience you're initializing
this from a vector anyway (it should really probably stored as a map internally
in this class), maybe it's better to just iterate over the vector and make Set
calls instead of adding a Reset method?

[Jay Civelli, 2017/02/09 22:08:26]

This is actually not used, a left over from me taking inspiration from
GlobalDescriptors.
Removed.

+
+ private:
+  friend struct DefaultSingletonTraits<FileDescriptorStore>;
+  FileDescriptorStore();
+  ~FileDescriptorStore();
+
+  Mapping descriptors_;
+};

[Ken Rockot(use gerrit already), 2017/02/09 17:17:27]

DISALLOW_COPY_AND_ASSIGN

[Jay Civelli, 2017/02/09 22:08:26]

Done.

+
+}  // namespace base
+
+#endif  // BASE_FILE_DESCRIPTOR_STORE_H_