Move power event handling logic from ui/ to base/ on Windows

base/system_monitor/system_monitor_win.cc

 // 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/system_monitor/system_monitor.h"
 
+#include "base/win/wrapped_window_proc.h"
+
 namespace base {
 
-void SystemMonitor::ProcessWmPowerBroadcastMessage(int event_id) {
+namespace {
+
+const wchar_t kWindowClassName[] = L"Base_PowerMessageWindow";
+
+}  // namespace
+
+void SystemMonitor::PlatformInit() {
+  power_message_window_.reset(new PowerMessageWindow(this));
+}
+
+void SystemMonitor::PlatformDestroy() {
+}
+
+// Function to query the system to see if it is currently running on
+// battery power.  Returns true if running on battery.
+bool SystemMonitor::IsBatteryPower() {
+  SYSTEM_POWER_STATUS status;
+  if (!GetSystemPowerStatus(&status)) {
+    DLOG_GETLASTERROR(ERROR) << "GetSystemPowerStatus failed";
+    return false;
+  }
+  return (status.ACLineStatus == 0);
+}
+
+SystemMonitor::PowerMessageWindow::PowerMessageWindow(SystemMonitor* monitor)
+    : monitor_(monitor), instance_(NULL), message_hwnd_(NULL) {
+  InitMessageHWND();
+}
+
+SystemMonitor::PowerMessageWindow::~PowerMessageWindow() {
+  if (message_hwnd_)
+    DestroyWindow(message_hwnd_);
+}
+
+void SystemMonitor::PowerMessageWindow::InitMessageHWND() {

[vandebo (ex-Chrome), 2013/02/20 22:30:40]

I think this can all go in the constructor.  It is in SystemMessageWindowClass. 
It's not in RemovableDeviceNotificationsWindowWin because in that case we need
the file thread to be running in order to examine the devices.

[Hongbo Min, 2013/02/21 07:39:08]

Make more sense. Done!

+  WNDCLASSEX window_class;
+  base::win::InitializeWindowClass(
+      kWindowClassName,
+      &base::win::WrappedWindowProc<
+          SystemMonitor::PowerMessageWindow::WndProcThunk>,
+      0, 0, 0, NULL, NULL, NULL, NULL, NULL,
+      &window_class);
+  instance_ = window_class.hInstance;
+  ATOM clazz = RegisterClassEx(&window_class);
+  DCHECK(clazz);
+
+  message_hwnd_ = CreateWindow(kWindowClassName,
+                         0, 0, 0, 0, 0, 0, HWND_MESSAGE, 0, instance_, 0);

[vandebo (ex-Chrome), 2013/02/20 22:30:40]

Are you sure you want HWND_MESSAGE as the parent?  The other places that do this
pass 0 as the parent.

[Hongbo Min, 2013/02/21 07:39:08]

I just saw MessagePumpForUI in message_pump_win.cc using HWND_MESSAGE to create
a message-only window.

After a double-check on CreateWindow function, I think it is not correct using
HWND_MESSAGE here. According to
http://msdn.microsoft.com/en-us/library/windows/desktop/ms632599(v=vs.85).asp...,
the message-only window has some special differences with a general window, for
example, it cannot be enumerated, and does not receive broadcast messages, and
simply dispatches messages.

So use 0 as parent instead.

+  SetWindowLongPtr(message_hwnd_, GWLP_USERDATA,
+                   reinterpret_cast<LONG_PTR>(this));
+}
+
+void SystemMonitor::PowerMessageWindow::ProcessWmPowerBroadcastMessage(
+    int event_id) {
   PowerEvent power_event;
   switch (event_id) {
     case PBT_APMPOWERSTATUSCHANGE:  // The power status changed.
-      power_event = POWER_STATE_EVENT;
+      power_event = SystemMonitor::POWER_STATE_EVENT;
       break;
     case PBT_APMRESUMEAUTOMATIC:  // Resume from suspend.
     //case PBT_APMRESUMESUSPEND:  // User-initiated resume from suspend.
                                   // We don't notify for this latter event
                                   // because if it occurs it is always sent as a
                                   // second event after PBT_APMRESUMEAUTOMATIC.
-      power_event = RESUME_EVENT;
+      power_event = SystemMonitor::RESUME_EVENT;
       break;
     case PBT_APMSUSPEND:  // System has been suspended.
-      power_event = SUSPEND_EVENT;
+      power_event = SystemMonitor::SUSPEND_EVENT;
       break;
     default:
       return;
 
     // Other Power Events:
     // PBT_APMBATTERYLOW - removed in Vista.
     // PBT_APMOEMEVENT - removed in Vista.
     // PBT_APMQUERYSUSPEND - removed in Vista.
     // PBT_APMQUERYSUSPENDFAILED - removed in Vista.
     // PBT_APMRESUMECRITICAL - removed in Vista.
     // PBT_POWERSETTINGCHANGE - user changed the power settings.
   }
-  ProcessPowerMessage(power_event);
+  monitor_->ProcessPowerMessage(power_event);

[vandebo (ex-Chrome), 2013/02/20 22:30:40]

Can we just call SystemMonitor::Get() here, that way the PowerMessageWindow
doesn't need to take the SystemMonitor in the constructor. That further means
that it could be a direct member of SystemMonitor and you wouldn't need
PlatformInit/Destory.

[Hongbo Min, 2013/02/21 07:39:08]

Done!

 }
 
-// Function to query the system to see if it is currently running on
-// battery power.  Returns true if running on battery.
-bool SystemMonitor::IsBatteryPower() {
-  SYSTEM_POWER_STATUS status;
-  if (!GetSystemPowerStatus(&status)) {
-    DLOG_GETLASTERROR(ERROR) << "GetSystemPowerStatus failed";
-    return false;
+LRESULT CALLBACK SystemMonitor::PowerMessageWindow::WndProc(
+    HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam) {
+  switch (message) {
+    case WM_POWERBROADCAST: {
+      DWORD power_event = static_cast<DWORD>(message);
+      ProcessWmPowerBroadcastMessage(power_event);
+      return TRUE;
+    }
+    default:
+      break;
   }
-  return (status.ACLineStatus == 0);
+  return TRUE;

[vandebo (ex-Chrome), 2013/02/20 22:30:40]

Should this also return ::DefWindowProc ?

[Hongbo Min, 2013/02/21 07:39:08]

Good catch! Done!

+}
+
+// static
+LRESULT CALLBACK SystemMonitor::PowerMessageWindow::WndProcThunk(
+    HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam) {
+  SystemMonitor::PowerMessageWindow* message_hwnd =
+      reinterpret_cast<SystemMonitor::PowerMessageWindow*>(
+          GetWindowLongPtr(hwnd, GWLP_USERDATA));
+  if (message_hwnd)
+    return message_hwnd->WndProc(hwnd, message, wparam, lparam);
+  return ::DefWindowProc(hwnd, message, wparam, lparam);
 }
 
 }  // namespace base