Use the correct null constants for Mach threads, tasks, and hosts

util/test/mac/mach_multiprocess.cc

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 37 matching lines @@
 namespace crashpad {
 namespace test {
 
 namespace internal {
 
 struct MachMultiprocessInfo {
   MachMultiprocessInfo()
       : service_name(),
         local_port(MACH_PORT_NULL),
         remote_port(MACH_PORT_NULL),
-        child_task(MACH_PORT_NULL) {}
+        child_task(TASK_NULL) {
+  }
 
   std::string service_name;
   base::mac::ScopedMachReceiveRight local_port;
   base::mac::ScopedMachSendRight remote_port;
   base::mac::ScopedMachSendRight child_task;  // valid only in parent
 };
 
 }  // namespace internal
 
 MachMultiprocess::MachMultiprocess() : Multiprocess(), info_(NULL) {
@@ skipping 36 matching lines @@
   EXPECT_NE(kMachPortNull, info_->local_port);
   return info_->local_port;
 }
 
 mach_port_t MachMultiprocess::RemotePort() const {
   EXPECT_NE(kMachPortNull, info_->remote_port);
   return info_->remote_port;
 }
 
 task_t MachMultiprocess::ChildTask() const {
-  EXPECT_NE(kMachPortNull, info_->child_task);
+  EXPECT_NE(TASK_NULL, info_->child_task);
   return info_->child_task;
 }
 
 void MachMultiprocess::MultiprocessParent() {
   ReceiveHelloMessage message = {};
 
   kern_return_t kr =
       mach_msg(&message.header,
                MACH_RCV_MSG | MACH_RCV_TRAILER_TYPE(MACH_MSG_TRAILER_FORMAT_0) |
                    MACH_RCV_TRAILER_ELEMENTS(MACH_RCV_TRAILER_AUDIT),
@@ skipping 143 matching lines @@
   if (testing::Test::HasFailure()) {
     // Trigger the ScopedForbidReturn destructor.
     return;
   }
 
   forbid_return.Disarm();
 }
 
 }  // namespace test
 }  // namespace crashpad