[Mac] Remove base::LaunchSynchronize and rewrite content::MachBroker.

base/mac/scoped_mach_port.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 BASE_MAC_SCOPED_MACH_PORT_H_
 #define BASE_MAC_SCOPED_MACH_PORT_H_
 
 #include <mach/mach.h>
 
 #include "base/basictypes.h"
 #include "base/base_export.h"
 
 namespace base {
 namespace mac {
 
 // A class for managing the life of a Mach port, releasing via
 // mach_port_deallocate either its send and/or receive rights.
 class BASE_EXPORT ScopedMachPort {
  public:
   // Creates a scoper by taking ownership of the port.
   explicit ScopedMachPort(mach_port_t port);
 
   ~ScopedMachPort();
 
+  void reset(mach_port_t port = MACH_PORT_NULL);
+
   operator mach_port_t() const {
     return port_;
   }
 
   mach_port_t get() const {
     return port_;
   }
 
  private:
   mach_port_t port_;
 
   DISALLOW_COPY_AND_ASSIGN(ScopedMachPort);
 };
 
 }  // namespace mac
 }  // namespace base
 
 #endif  // BASE_MAC_SCOPED_MACH_PORT_H_