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

ui/views/win/hwnd_message_handler.cc

 // 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.
 
 #include "ui/views/win/hwnd_message_handler.h"
 
 #include <dwmapi.h>
 #include <shellapi.h>
 
 #include "base/bind.h"
-#include "base/system_monitor/system_monitor.h"
+#include "base/power_monitor/power_monitor.h"
 #include "base/win/windows_version.h"
 #include "ui/base/events/event.h"
 #include "ui/base/keycodes/keyboard_code_conversion_win.h"
 #include "ui/base/native_theme/native_theme_win.h"
 #include "ui/base/win/hwnd_util.h"
 #include "ui/base/win/mouse_wheel_util.h"
 #include "ui/base/win/shell.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/canvas_paint.h"
 #include "ui/gfx/canvas_skia_paint.h"
@@ skipping 11 matching lines @@
 #include "ui/views/win/scoped_fullscreen_visibility.h"
 
 #if !defined(USE_AURA)
 #include "ui/views/accessibility/native_view_accessibility_win.h"
 #include "ui/views/widget/child_window_message_processor.h"
 #endif
 
 namespace views {
 namespace {
 
+// Reference the Signaler defined in the global PowerMonitor instance.

[vandebo (ex-Chrome), 2012/10/29 18:04:38]

Remove or update this comment to say *why* this is here.

[Hongbo Min, 2012/10/30 14:33:47]

Done.

+base::PowerMonitor::Signaler* g_power_signaler = NULL;
+
 // MoveLoopMouseWatcher is used to determine if the user canceled or completed a
 // move. win32 doesn't appear to offer a way to determine the result of a move,
 // so we install hooks to determine if we got a mouse up and assume the move
 // completed.
 class MoveLoopMouseWatcher {
  public:
   explicit MoveLoopMouseWatcher(HWNDMessageHandler* host);
   ~MoveLoopMouseWatcher();
 
   // Returns true if the mouse is up, or if we couldn't install the hook.
@@ skipping 325 matching lines @@
       is_right_mouse_pressed_on_caption_(false),
       lock_updates_count_(0),
       destroyed_(NULL),
       ignore_window_pos_changes_(false),
       ALLOW_THIS_IN_INITIALIZER_LIST(ignore_pos_changes_factory_(this)),
       last_monitor_(NULL),
       use_layered_buffer_(false),
       layered_alpha_(255),
       ALLOW_THIS_IN_INITIALIZER_LIST(paint_layered_window_factory_(this)),
       can_update_layered_window_(true) {
+  if (g_power_signaler == NULL && base::PowerMonitor::Get())
+    g_power_signaler = base::PowerMonitor::Get()->GetSignalerOnce();
 }
 
 HWNDMessageHandler::~HWNDMessageHandler() {
   delegate_ = NULL;
   if (destroyed_ != NULL)
     *destroyed_ = true;
   // Prevent calls back into this class via WNDPROC now that we've been
   // destroyed.
   ClearUserData();
 }
@@ skipping 1442 matching lines @@
 #endif
     }
   } else {
     // TODO(msw): Find a better solution for this crbug.com/93530 workaround.
     // Some scenarios otherwise fail to validate minimized app/popup windows.
     ValidateRect(hwnd(), NULL);
   }
 }
 
 LRESULT HWNDMessageHandler::OnPowerBroadcast(DWORD power_event, DWORD data) {
-  base::SystemMonitor* monitor = base::SystemMonitor::Get();
-  if (monitor)
-    monitor->ProcessWmPowerBroadcastMessage(power_event);
+  CHECK(!g_power_signaler);
+  g_power_signaler->ProcessWmPowerBroadcastMessage(power_event);
+
   SetMsgHandled(FALSE);
   return 0;
 }
 
 LRESULT HWNDMessageHandler::OnReflectedMessage(UINT message,
                                                WPARAM w_param,
                                                LPARAM l_param) {
   SetMsgHandled(FALSE);
   return 0;
 }
@@ skipping 212 matching lines @@
     DwmExtendFrameIntoClientArea(hwnd(), &m);
   }
   if (window_pos->flags & SWP_SHOWWINDOW)
     delegate_->HandleVisibilityChanged(true);
   else if (window_pos->flags & SWP_HIDEWINDOW)
     delegate_->HandleVisibilityChanged(false);
   SetMsgHandled(FALSE);
 }
 
 }  // namespace views