SystemMonitor refactoring: move power state monitor into a separate class called PowerMonitor

base/power_monitor/power_monitor_mac.mm

 // 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.
 
 // Implementation based on sample code from
 // http://developer.apple.com/library/mac/#qa/qa1340/_index.html.
 
-#include "base/system_monitor/system_monitor.h"
+#include "base/power_monitor/power_monitor.h"
 
 #include <IOKit/pwr_mgt/IOPMLib.h>
 #include <IOKit/IOMessage.h>
 
 namespace base {
 
 namespace {
 
 io_connect_t g_system_power_io_port = 0;
 IONotificationPortRef g_notification_port_ref = 0;
 io_object_t g_notifier_object = 0;
+PowerMonitor::Signaler* g_power_signaler = NULL;
 
 void SystemPowerEventCallback(void*,
                               io_service_t service,
                               natural_t message_type,
                               void* message_argument) {
-  SystemMonitor* sys_monitor = SystemMonitor::Get();
-  DCHECK(sys_monitor);
+
+  CHECK(g_power_signaler);
   switch (message_type) {
     case kIOMessageSystemWillSleep:
-      sys_monitor->ProcessPowerMessage(SystemMonitor::SUSPEND_EVENT);
+      g_power_signaler->ProcessPowerEvent(base::PowerMonitor::SUSPEND_EVENT);
       IOAllowPowerChange(g_system_power_io_port,
           reinterpret_cast<intptr_t>(message_argument));
       break;
 
     case kIOMessageSystemWillPowerOn:
-      sys_monitor->ProcessPowerMessage(SystemMonitor::RESUME_EVENT);
+      g_power_signaler->ProcessPowerEvent(PowerMonitor::RESUME_EVENT);
       break;
   }
 }
 
 }  // namespace
 
 // The reason we can't include this code in the constructor is because
 // PlatformInit() requires an active runloop and the IO port needs to be
 // allocated at sandbox initialization time, before there's a runloop.
 // See crbug.com/83783 .
 
 // static
-void SystemMonitor::AllocateSystemIOPorts() {
+void PowerMonitor::AllocateSystemIOPorts() {
   DCHECK_EQ(g_system_power_io_port, 0u);
+  if (g_system_power_io_port != 0u)
+    return;
 
   // Notification port allocated by IORegisterForSystemPower.
 
   g_system_power_io_port = IORegisterForSystemPower(
       NULL, &g_notification_port_ref, SystemPowerEventCallback,
       &g_notifier_object);
 
   DCHECK_NE(g_system_power_io_port, 0u);
 }
 
-void SystemMonitor::PlatformInit() {
-  // Need to call AllocateSystemIOPorts() before constructing a SystemMonitor
+void PowerMonitor::PlatformInit() {
+  // Need to call AllocateSystemIOPorts() before creating a PowerMonitor
   // object.
-  DCHECK_NE(g_system_power_io_port, 0u);
-  if (g_system_power_io_port == 0)
-    return;
+  CHECK_NE(g_system_power_io_port, 0u);
+ 
+  CHECK(!g_power_signaler);
+  g_power_signaler = PowerMonitor::Get()->GetSignalerOnce();
 
   // Add the notification port to the application runloop
   CFRunLoopAddSource(
       CFRunLoopGetCurrent(),
       IONotificationPortGetRunLoopSource(g_notification_port_ref),
       kCFRunLoopCommonModes);
 }
 
-void SystemMonitor::PlatformDestroy() {
+
+void PowerMonitor::PlatformDestroy() {
   DCHECK_NE(g_system_power_io_port, 0u);
+
   if (g_system_power_io_port == 0)
     return;
 
   // Remove the sleep notification port from the application runloop
   CFRunLoopRemoveSource(
       CFRunLoopGetCurrent(),
       IONotificationPortGetRunLoopSource(g_notification_port_ref),
       kCFRunLoopCommonModes);
 
   // Deregister for system sleep notifications
   IODeregisterForSystemPower(&g_notifier_object);
 
   // IORegisterForSystemPower implicitly opens the Root Power Domain IOService,
   // so we close it here.
   IOServiceClose(g_system_power_io_port);
 
   g_system_power_io_port = 0;
 
   // Destroy the notification port allocated by IORegisterForSystemPower.
   IONotificationPortDestroy(g_notification_port_ref);
 }
 
 }  // namespace base