// Copyright 2013 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_POWER_MONITOR_POWER_MONITOR_SOURCE_H_
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#define BASE_POWER_MONITOR_POWER_MONITOR_SOURCE_H_
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#include "base/base_export.h"
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#include "base/macros.h"
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#include "base/memory/ref_counted.h"
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#include "base/observer_list_threadsafe.h"
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#include "base/synchronization/lock.h"
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namespace base {
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class PowerMonitor;
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// Communicates power state changes to the power monitor.
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class BASE_EXPORT PowerMonitorSource {
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public:
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PowerMonitorSource();
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virtual ~PowerMonitorSource();
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// Normalized list of power events.
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enum PowerEvent {
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POWER_STATE_EVENT, // The Power status of the system has changed.
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SUSPEND_EVENT, // The system is being suspended.
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RESUME_EVENT // The system is being resumed.
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};
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// Is the computer currently on battery power. Can be called on any thread.
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bool IsOnBatteryPower();
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// Called by PowerMonitor just before PowerMonitor destroys both itself and
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// this instance). After return from this call it is no longer safe for
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// subclasses to call into PowerMonitor (e.g., via PowerMonitor::Get(). Hence,
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// subclasses should take any necessary actions here to ensure that after
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// return from this invocation they will no longer make any calls on
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// PowerMonitor.
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virtual void Shutdown() = 0;
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protected:
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friend class PowerMonitorTest;
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// Friend function that is allowed to access the protected ProcessPowerEvent.
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friend void ProcessPowerEventHelper(PowerEvent);
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// ProcessPowerEvent should only be called from a single thread, most likely
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// the UI thread or, in child processes, the IO thread.
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static void ProcessPowerEvent(PowerEvent event_id);
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// Platform-specific method to check whether the system is currently
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// running on battery power. Returns true if running on batteries,
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// false otherwise.
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virtual bool IsOnBatteryPowerImpl() = 0;
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// Sets the initial state for |on_battery_power_|, which defaults to false
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// since not all implementations can provide the value at construction. May
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// only be called before a base::PowerMonitor has been created.
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void SetInitialOnBatteryPowerState(bool on_battery_power);
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private:
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bool on_battery_power_ = false;
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bool suspended_ = false;
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// This lock guards access to on_battery_power_, to ensure that
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// IsOnBatteryPower can be called from any thread.
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Lock battery_lock_;
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DISALLOW_COPY_AND_ASSIGN(PowerMonitorSource);
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};
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} // namespace base
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#endif // BASE_POWER_MONITOR_POWER_MONITOR_SOURCE_H_
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