Created multi-process-friendly PowerMonitor interface.

base/power_monitor/power_monitor.h

 // Copyright 2013 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_POWER_MONITOR_POWER_MONITOR_H_
 #define BASE_POWER_MONITOR_POWER_MONITOR_H_
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/observer_list_threadsafe.h"
 #include "base/power_monitor/power_observer.h"
 
-#if defined(OS_WIN)
-#include <windows.h>
+namespace base {
 
-// Windows HiRes timers drain the battery faster so we need to know the battery
-// status.  This isn't true for other platforms.
-#define ENABLE_BATTERY_MONITORING 1
-#else
-#undef ENABLE_BATTERY_MONITORING
-#endif  // !OS_WIN
-
-#if defined(ENABLE_BATTERY_MONITORING)
-#include "base/timer/timer.h"
-#endif  // defined(ENABLE_BATTERY_MONITORING)
-
-#if defined(OS_IOS)
-#include <objc/runtime.h>
-#endif  // OS_IOS
-
-namespace base {
+class PowerMonitorSource;
 
 // A class used to monitor the power state change and notify the observers about
 // the change event.
 class BASE_EXPORT PowerMonitor {
  public:
-  // Normalized list of power events.
-  enum PowerEvent {
-    POWER_STATE_EVENT,  // The Power status of the system has changed.
-    SUSPEND_EVENT,      // The system is being suspended.
-    RESUME_EVENT        // The system is being resumed.
-  };
-
+  // The default constructor should only be used in the browser process. All
+  // other processes should explicitly pass an appropriate PowerMonitorSource
   PowerMonitor();
+  // Takes ownership of |source|.
+  explicit PowerMonitor(PowerMonitorSource* source);

[piman, 2013/07/12 21:09:58]

nit: pass a scoped_ptr instead to make it obvious (on the caller site) that it
takes ownership.

   ~PowerMonitor();
 
-  // Get the application-wide PowerMonitor (if not present, returns NULL).
+  // Get the process-wide PowerMonitor (if not present, returns NULL).
   static PowerMonitor* Get();
 
-#if defined(OS_MACOSX)
-  // Allocate system resources needed by the PowerMonitor class.
-  //
-  // This function must be called before instantiating an instance of the class
-  // and before the Sandbox is initialized.
-#if !defined(OS_IOS)
-  static void AllocateSystemIOPorts();
-#else
-  static void AllocateSystemIOPorts() {}
-#endif  // OS_IOS
-#endif  // OS_MACOSX
-
   // Add and remove an observer.
   // Can be called from any thread.
   // Must not be called from within a notification callback.
   void AddObserver(PowerObserver* observer);
   void RemoveObserver(PowerObserver* observer);
 
-  // Is the computer currently on battery power. Can be called on any thread.
-  bool BatteryPower() const {
-    // Using a lock here is not necessary for just a bool.
-    return battery_in_use_;
-  }
+  // Is the computer currently on battery power.
+  bool IsOnBatteryPower();
 
  private:
-  friend class PowerMonitorTest;
-  // A friend function that is allowed to access the private ProcessPowerEvent.
-  friend void ProcessPowerEventHelper(PowerEvent);
+  friend class PowerMonitorSource;
 
-#if defined(OS_WIN)
-  // Represents a message-only window for power message handling on Windows.
-  // Only allow PowerMonitor to create it.
-  class PowerMessageWindow {
-   public:
-    PowerMessageWindow();
-    ~PowerMessageWindow();
+  PowerMonitorSource* Source();
 
-   private:
-    void ProcessWmPowerBroadcastMessage(int event_id);
-    LRESULT CALLBACK WndProc(HWND hwnd, UINT message,
-                             WPARAM wparam, LPARAM lparam);
-    static LRESULT CALLBACK WndProcThunk(HWND hwnd,
-                                         UINT message,
-                                         WPARAM wparam,
-                                         LPARAM lparam);
-    // Instance of the module containing the window procedure.
-    HMODULE instance_;
-    // A hidden message-only window.
-    HWND message_hwnd_;
-  };
-#endif  // OS_WIN
-
-#if defined(OS_MACOSX)
-  void PlatformInit();
-  void PlatformDestroy();
-#endif
-
-  // Cross-platform handling of a power event.
-  void ProcessPowerEvent(PowerEvent event_id);
-
-  // Platform-specific method to check whether the system is currently
-  // running on battery power.  Returns true if running on batteries,
-  // false otherwise.
-  bool IsBatteryPower();
-
-  // Checks the battery status and notifies observers if the battery
-  // status has changed.
-  void BatteryCheck();
-
-  void NotifyPowerStateChange();
+  void NotifyPowerStateChange(bool battery_in_use);
   void NotifySuspend();
   void NotifyResume();
 
-#if defined(OS_IOS)
-  // Holds pointers to system event notification observers.
-  std::vector<id> notification_observers_;
-#endif
-
-#if defined(ENABLE_BATTERY_MONITORING)
-  base::OneShotTimer<PowerMonitor> delayed_battery_check_;
-#endif
-
   scoped_refptr<ObserverListThreadSafe<PowerObserver> > observers_;
-  bool battery_in_use_;
-  bool suspended_;
-
-#if defined(OS_WIN)
-  PowerMessageWindow power_message_window_;
-#endif
+  scoped_ptr<PowerMonitorSource> source_;
 
   DISALLOW_COPY_AND_ASSIGN(PowerMonitor);
 };
 
 }  // namespace base
 
 #endif  // BASE_POWER_MONITOR_POWER_MONITOR_H_