Repo created

TMessagesProj/jni/voip/webrtc/base/system/system_monitor.h

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+// 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.
+
+#ifndef BASE_SYSTEM_SYSTEM_MONITOR_H_
+#define BASE_SYSTEM_SYSTEM_MONITOR_H_
+
+#include "base/base_export.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.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();
+
+  // 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_;
+
+  DISALLOW_COPY_AND_ASSIGN(SystemMonitor);
+};
+
+}  // namespace base
+
+#endif  // BASE_SYSTEM_SYSTEM_MONITOR_H_