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);
+  PowerMonitor* power_monitor = PowerMonitor::Get();
+  CHECK(power_monitor);
+  if (!g_power_signaler)

[Hongbo Min, 2012/10/31 13:11:38]

g_power_signaler gets initialized here instead of PlatformInit  because it can
facilitate the testing code for GetSignalerOnce.

If the g_power_signaler is assigned in the PlatformInit, it means that we can't
not easily test the GetSignalerOnce for the first time calling.

From the sequence of initialization on other platforms, the g_power_signaler
only gets initialized on-demand.

I don't think that we need to free g_power_signaler in PlatformDestroy because
current implementation will not crash the application even the lifetime of
Signaler is longer than that of PowerMonitor's.

[vandebo (ex-Chrome), 2012/10/31 17:30:34]

Hmm, I think it's better to get it in PlatformInit and we can still make the
test work.  PowerMonitorTest can friend PowerMonitor and reset
is_signaler_available_ in its SetUp method to get its own signaler.
 
I think it's better to make PlatformInit valid on all platforms and get the
signaler in there if possible (doesn't work for Windows).
It won't crash, but it will leak and our memory tests will see that.  We can
clean up the memory, so we should.

You can run the linux_valgrind bot or win_drmemory to tests memory issues.

[Hongbo Min, 2012/11/01 09:26:24]

Right now the PlatformInit/PlatformDestroy is available for all platform
although empty impl on Windows.

+    g_power_signaler = power_monitor->GetSignalerOnce();
+
   switch (message_type) {
     case kIOMessageSystemWillSleep:
-      sys_monitor->ProcessPowerMessage(SystemMonitor::SUSPEND_EVENT);
+      if (g_power_signaler)
+        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);
+      if (g_power_signaler)
+        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);
+ 
 
   // 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