Mojo: Move system embedder API files to mojo/system/embedder.

mojo/system/platform_channel_pair.h

-// Copyright 2014 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 MOJO_SYSTEM_PLATFORM_CHANNEL_PAIR_H_
-#define MOJO_SYSTEM_PLATFORM_CHANNEL_PAIR_H_
-
-#include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/process/launch.h"
-#include "mojo/system/scoped_platform_handle.h"
-#include "mojo/system/system_impl_export.h"
-
-class CommandLine;
-
-namespace mojo {
-namespace embedder {
-
-// This is used to create a pair of |PlatformHandle|s that are connected by a
-// suitable (platform-specific) bidirectional "pipe" (e.g., socket on POSIX,
-// named pipe on Windows). The resulting handles can then be used in the same
-// process (e.g., in tests) or between processes. (The "server" handle is the
-// one that will be used in the process that created the pair, whereas the
-// "client" handle is the one that will be used in a different process.)
-//
-// This class provides facilities for passing the client handle to a child
-// process. The parent should call |PrepareToPassClientHandlelToChildProcess()|
-// to get the data needed to do this, spawn the child using that data, and then
-// call |ChildProcessLaunched()|. Note that on Windows this facility (will) only
-// work on Vista and later (TODO(vtl)).
-//
-// Note: |PlatformChannelPair()|, |PassClientHandleFromParentProcess()|,
-// |PrepareToPassClientHandleToChildProcess()|, and |ChildProcessLaunched()|
-// have platform-specific implementations.
-class MOJO_SYSTEM_IMPL_EXPORT PlatformChannelPair {
- public:
-  PlatformChannelPair();
-  ~PlatformChannelPair();
-
-  ScopedPlatformHandle PassServerHandle();
-
-  // For in-process use (e.g., in tests).
-  ScopedPlatformHandle PassClientHandle();
-
-  // To be called in the child process, after the parent process called
-  // |PrepareToPassClientHandleToChildProcess()| and launched the child (using
-  // the provided data), to create a client handle connected to the server
-  // handle (in the parent process).
-  static ScopedPlatformHandle PassClientHandleFromParentProcess(
-      const CommandLine& command_line);
-
-  // Prepares to pass the client channel to a new child process, to be launched
-  // using |LaunchProcess()| (from base/launch.h). Modifies |*command_line| and
-  // |*file_handle_mapping| as needed. (|file_handle_mapping| may be null on
-  // platforms that don't need it, like Windows.)
-  void PrepareToPassClientHandleToChildProcess(
-      CommandLine* command_line,
-      base::FileHandleMappingVector* file_handle_mapping) const;
-  // To be called once the child process has been successfully launched, to do
-  // any cleanup necessary.
-  void ChildProcessLaunched();
-
- private:
-  ScopedPlatformHandle server_handle_;
-  ScopedPlatformHandle client_handle_;
-
-  DISALLOW_COPY_AND_ASSIGN(PlatformChannelPair);
-};
-
-}  // namespace embedder
-}  // namespace mojo
-
-#endif  // MOJO_SYSTEM_PLATFORM_CHANNEL_PAIR_H_