Use PathService to get temp dir name for IPC unittests.

ipc/unix_domain_socket_util_unittest.cc

 // Copyright 2013 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 <sys/socket.h>
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/path_service.h"
 #include "base/posix/eintr_wrapper.h"
@@ skipping 60 matching lines @@
   int server_fd_;
   base::MessageLoopProxy* target_thread_;
   scoped_ptr<base::MessageLoopForIO::FileDescriptorWatcher> watcher_;
   base::WaitableEvent started_watching_event_;
   base::WaitableEvent accepted_event_;
 
   DISALLOW_COPY_AND_ASSIGN(SocketAcceptor);
 };
 
 const base::FilePath GetChannelDir() {
-#if defined(OS_ANDROID)
   base::FilePath tmp_dir;
-  PathService::Get(base::DIR_CACHE, &tmp_dir);
+  PathService::Get(base::DIR_TEMP, &tmp_dir);
   return tmp_dir;
-#else
-  return base::FilePath("/var/tmp");
-#endif
 }
 
 class TestUnixSocketConnection {
  public:
   TestUnixSocketConnection()
       : worker_("WorkerThread"),
         server_listen_fd_(-1),
         server_fd_(-1),
         client_fd_(-1) {
     socket_name_ = GetChannelDir().Append("TestSocket");
@@ skipping 68 matching lines @@
       HANDLE_EINTR(send(connection.client_fd(), buffer, buf_len, 0));
   ASSERT_EQ(buf_len, sent_bytes);
   char recv_buf[sizeof(buffer)];
   size_t received_bytes =
       HANDLE_EINTR(recv(connection.server_fd(), recv_buf, buf_len, 0));
   ASSERT_EQ(buf_len, received_bytes);
   ASSERT_EQ(0, memcmp(recv_buf, buffer, buf_len));
 }
 
 }  // namespace