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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_SYSTEM_SYSTEM_MONITOR_H_
#define BASE_SYSTEM_SYSTEM_MONITOR_H_
#include "base/base_export.h"
#include "base/observer_list_threadsafe.h"
#include "build/build_config.h"
namespace base {
// Class for monitoring various system-related subsystems
// such as power management, network status, etc.
// TODO(mbelshe): Add support beyond just power management.
class BASE_EXPORT SystemMonitor {
public:
// Type of devices whose change need to be monitored, such as add/remove.
enum DeviceType {
DEVTYPE_AUDIO, // Audio device, e.g., microphone.
DEVTYPE_VIDEO_CAPTURE, // Video capture device, e.g., webcam.
DEVTYPE_UNKNOWN, // Other devices.
};
// Create SystemMonitor. Only one SystemMonitor instance per application
// is allowed.
SystemMonitor();
SystemMonitor(const SystemMonitor&) = delete;
SystemMonitor& operator=(const SystemMonitor&) = delete;
~SystemMonitor();
// Get the application-wide SystemMonitor (if not present, returns NULL).
static SystemMonitor* Get();
class BASE_EXPORT DevicesChangedObserver {
public:
// Notification that the devices connected to the system have changed.
// This is only implemented on Windows currently.
virtual void OnDevicesChanged(DeviceType device_type) {}
protected:
virtual ~DevicesChangedObserver() = default;
};
// Add a new observer.
// Can be called from any thread.
// Must not be called from within a notification callback.
void AddDevicesChangedObserver(DevicesChangedObserver* obs);
// Remove an existing observer.
// Can be called from any thread.
// Must not be called from within a notification callback.
void RemoveDevicesChangedObserver(DevicesChangedObserver* obs);
// The ProcessFoo() style methods are a broken pattern and should not
// be copied. Any significant addition to this class is blocked on
// refactoring to improve the state of affairs. See http://crbug.com/149059
// Cross-platform handling of a device change event.
void ProcessDevicesChanged(DeviceType device_type);
private:
// Functions to trigger notifications.
void NotifyDevicesChanged(DeviceType device_type);
scoped_refptr<ObserverListThreadSafe<DevicesChangedObserver>>
devices_changed_observer_list_;
};
} // namespace base
#endif // BASE_SYSTEM_SYSTEM_MONITOR_H_
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