[mojo-edk] Add support for transferring mach ports.

mojo/edk/system/mach_port_relay.h

+// Copyright 2016 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_EDK_SYSTEM_MACH_PORT_RELAY_H_
+#define MOJO_EDK_SYSTEM_MACH_PORT_RELAY_H_
+
+#include <set>
+
+#include "base/macros.h"
+#include "base/process/port_provider_mac.h"
+#include "base/synchronization/lock.h"
+#include "mojo/edk/embedder/scoped_platform_handle.h"
+#include "mojo/edk/system/channel.h"
+
+namespace mojo {
+namespace edk {
+
+class MachPortRelay : public base::PortProvider::Observer {
+ public:
+  class Observer {
+   public:
+    virtual void OnProcessReady(base::ProcessHandle process) = 0;
+  };
+
+  static bool ReceivePorts(PlatformHandleVector* handles);
+
+  explicit MachPortRelay(base::PortProvider* port_provider);
+  ~MachPortRelay() override;
+
+  bool SendPortsToProcess(Channel::Message* message,
+                          base::ProcessHandle process);
+
+  bool ExtractPortRights(Channel::Message* message,
+                         base::ProcessHandle process);
+
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+  base::PortProvider* port_provider() const { return port_provider_; }
+
+ private:
+  // base::PortProvider::Observer implementation.
+  void OnReceivedTaskPort(base::ProcessHandle process) override;
+
+  base::PortProvider* const port_provider_;
+
+  base::Lock observers_lock_;
+  std::set<Observer*> observers_;
+
+  DISALLOW_COPY_AND_ASSIGN(MachPortRelay);
+};
+
+}  // namespace edk
+}  // namespace mojo
+
+#endif  // MOJO_EDK_SYSTEM_MACH_PORT_RELAY_H_