Revert of Add support for backgrounding processes on the Mac

base/process/process_posix.cc

-// Copyright 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 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 "base/process/process.h"
 
 #include <sys/resource.h>
 #include <sys/wait.h>
 
 #include "base/files/scoped_file.h"
 #include "base/logging.h"
@@ skipping 234 matching lines @@
   // On POSIX there are no privileges to set.
   return Open(pid);
 }
 
 // static
 Process Process::DeprecatedGetProcessFromHandle(ProcessHandle handle) {
   DCHECK_NE(handle, GetCurrentProcessHandle());
   return Process(handle);
 }
 
-#if !defined(OS_LINUX) && !defined(OS_MACOSX)
+#if !defined(OS_LINUX)
 // static
 bool Process::CanBackgroundProcesses() {
   return false;
 }
-#endif  // !defined(OS_LINUX) && !defined(OS_MACOSX)
+#endif  // !defined(OS_LINUX)
 
 bool Process::IsValid() const {
   return process_ != kNullProcessHandle;
 }
 
 ProcessHandle Process::Handle() const {
   return process_;
 }
 
 Process Process::Duplicate() const {
@@ skipping 74 matching lines @@
 #endif  // !defined(OS_NACL_NONSFI)
 
 bool Process::WaitForExit(int* exit_code) {
   return WaitForExitWithTimeout(TimeDelta::Max(), exit_code);
 }
 
 bool Process::WaitForExitWithTimeout(TimeDelta timeout, int* exit_code) {
   return WaitForExitWithTimeoutImpl(Handle(), exit_code, timeout);
 }
 
-#if !defined(OS_LINUX) && !defined(OS_MACOSX)
+#if !defined(OS_LINUX)
 bool Process::IsProcessBackgrounded() const {
   // See SetProcessBackgrounded().
   DCHECK(IsValid());
   return false;
 }
 
 bool Process::SetProcessBackgrounded(bool value) {
-  // Not implemented for POSIX systems other than Mac and Linux. With POSIX, if
-  // we were to lower the process priority we wouldn't be able to raise it back
-  // to its initial priority.
-  NOTIMPLEMENTED();
+  // POSIX only allows lowering the priority of a process, so if we
+  // were to lower it we wouldn't be able to raise it back to its initial
+  // priority.
+  DCHECK(IsValid());
   return false;
 }
-#endif  // !defined(OS_LINUX) && !defined(OS_MACOSX)
+#endif  // !defined(OS_LINUX)
 
 int Process::GetPriority() const {
   DCHECK(IsValid());
   return getpriority(PRIO_PROCESS, process_);
 }
 
 }  // namespace base