Move DispatchSourceMach from //sandbox/mac to //base/mac.

sandbox/mac/dispatch_source_mach.cc

-// Copyright 2014 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 "sandbox/mac/dispatch_source_mach.h"
-
-namespace sandbox {
-
-DispatchSourceMach::DispatchSourceMach(const char* name,
-                                       mach_port_t port,
-                                       void (^event_handler)())
-    // TODO(rsesek): Specify DISPATCH_QUEUE_SERIAL, in the 10.7 SDK. NULL
-    // means the same thing but is not symbolically clear.
-    : DispatchSourceMach(dispatch_queue_create(name, NULL),
-                         port,
-                         event_handler) {
-  // Since the queue was created above in the delegated constructor, and it was
-  // subsequently retained, release it here.
-  dispatch_release(queue_);
-}
-
-DispatchSourceMach::DispatchSourceMach(dispatch_queue_t queue,
-                                       mach_port_t port,
-                                       void (^event_handler)())
-    : queue_(queue),
-      source_(dispatch_source_create(DISPATCH_SOURCE_TYPE_MACH_RECV,
-          port, 0, queue_)),
-      source_canceled_(dispatch_semaphore_create(0)) {
-  dispatch_retain(queue);
-
-  dispatch_source_set_event_handler(source_, event_handler);
-  dispatch_source_set_cancel_handler(source_, ^{
-      dispatch_semaphore_signal(source_canceled_);
-  });
-}
-
-DispatchSourceMach::~DispatchSourceMach() {
-  Cancel();
-}
-
-void DispatchSourceMach::Resume() {
-  dispatch_resume(source_);
-}
-
-void DispatchSourceMach::Cancel() {
-  if (source_) {
-    dispatch_source_cancel(source_);
-    dispatch_release(source_);
-    source_ = NULL;
-
-    dispatch_semaphore_wait(source_canceled_, DISPATCH_TIME_FOREVER);
-    dispatch_release(source_canceled_);
-    source_canceled_ = NULL;
-  }
-
-  if (queue_) {
-    dispatch_release(queue_);
-    queue_ = NULL;
-  }
-}
-
-}  // namespace sandbox