Use base::GlobalDescriptors::kBaseDescriptor instead of magic number 3.

ipc/ipc_test_base.cc

 // 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.
 
 #include "build/build_config.h"
 
 #include "ipc/ipc_test_base.h"
 
 #include "base/command_line.h"
 #include "base/debug/debug_on_start_win.h"
 #include "base/process/kill.h"
 #include "base/threading/thread.h"
 #include "base/time/time.h"
 #include "ipc/ipc_descriptors.h"
 #include "ipc/ipc_switches.h"
 
+#if defined(OS_POSIX)
+#include "base/posix/global_descriptors.h"
+#endif
+
 // static
 std::string IPCTestBase::GetChannelName(const std::string& test_client_name) {
   DCHECK(!test_client_name.empty());
   return test_client_name + "__Channel";
 }
 
 IPCTestBase::IPCTestBase()
     : client_process_(base::kNullProcessHandle) {
 }
 
@@ skipping 68 matching lines @@
   bool debug_on_start =
       CommandLine::ForCurrentProcess()->HasSwitch(switches::kDebugChildren);
 
 #if defined(OS_WIN)
   client_process_ = MultiProcessTest::SpawnChild(test_main, debug_on_start);
 #elif defined(OS_POSIX)
   base::FileHandleMappingVector fds_to_map;
   const int ipcfd = channel_.get() ? channel_->GetClientFileDescriptor() :
                                      channel_proxy_->GetClientFileDescriptor();
   if (ipcfd > -1)
-    fds_to_map.push_back(std::pair<int, int>(ipcfd, kPrimaryIPCChannel + 3));
+    fds_to_map.push_back(std::pair<int, int>(ipcfd,
+        kPrimaryIPCChannel + base::GlobalDescriptors::kBaseDescriptor));
 
   client_process_ = MultiProcessTest::SpawnChild(test_main,
                                                  fds_to_map,
                                                  debug_on_start);
 #endif
 
   return client_process_ != base::kNullProcessHandle;
 }
 
 bool IPCTestBase::WaitForClientShutdown() {
   DCHECK(client_process_ != base::kNullProcessHandle);
 
   bool rv = base::WaitForSingleProcess(client_process_,
                                        base::TimeDelta::FromSeconds(5));
   base::CloseProcessHandle(client_process_);
   client_process_ = base::kNullProcessHandle;
   return rv;
 }