Set unregistered handles to NULL in BatteryStatusObserver::Stop

device/battery/battery_status_manager_win.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 "device/battery/battery_status_manager_win.h"
 
 #include "base/bind.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string16.h"
@@ skipping 65 matching lines @@
     } else {
       // Could not create a message window, execute callback with the default
       // values.
       callback_.Run(BatteryStatus());
     }
 
     UpdateNumberBatteriesHistogram();
   }
 
   void Stop() {
-    if (power_handle_)
+    if (power_handle_) {
       UnregisterNotification(power_handle_);
-    if (battery_change_handle_)
+      power_handle_ = NULL;
+    }
+    if (battery_change_handle_) {
       UnregisterNotification(battery_change_handle_);
+      battery_change_handle_ = NULL;
+    }
     window_.reset();
   }
 
  private:
   void BatteryChanged() {
     SYSTEM_POWER_STATUS win_status;
     if (GetSystemPowerStatus(&win_status))
       callback_.Run(ComputeWebBatteryStatus(win_status));
     else
       callback_.Run(BatteryStatus());
@@ skipping 103 matching lines @@
 }
 
 // static
 scoped_ptr<BatteryStatusManager> BatteryStatusManager::Create(
     const BatteryStatusService::BatteryUpdateCallback& callback) {
   return scoped_ptr<BatteryStatusManager>(
       new BatteryStatusManagerWin(callback));
 }
 
 }  // namespace device