Base: Add power requirements to the System monitor.

base/system_monitor/system_monitor.h

 // 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_MONITOR_SYSTEM_MONITOR_H_
 #define BASE_SYSTEM_MONITOR_SYSTEM_MONITOR_H_
 #pragma once
 
+#include <map>
 #include <string>
+#include <utility>
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
+#include "base/threading/thread_checker.h"
 #include "build/build_config.h"
 
 // Windows HiRes timers drain the battery faster so we need to know the battery
 // status.  This isn't true for other platforms.
 #if defined(OS_WIN)
 #define ENABLE_BATTERY_MONITORING 1
 #else
 #undef ENABLE_BATTERY_MONITORING
 #endif  // !OS_WIN
 
@@ skipping 16 matching lines @@
 // TODO(mbelshe):  Add support beyond just power management.
 class BASE_EXPORT SystemMonitor {
  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.
   };
 
+  enum PowerRequirement {
+    DISPLAY_REQUIRED,   // The display should not be shut down.
+    SYSTEM_REQUIRED,    // The system should not be suspended.
+    CPU_REQUIRED,       // The process should not be suspended.
+    TEST_REQUIRED       // This is used by unit tests.
+  };
+
   typedef unsigned int DeviceIdType;
 
   // 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();
 
@@ skipping 79 matching lines @@
   // Cross-platform handling of a power event.
   void ProcessPowerMessage(PowerEvent event_id);
 
   // Cross-platform handling of a device change event.
   void ProcessDevicesChanged();
   void ProcessMediaDeviceAttached(const DeviceIdType& id,
                                   const std::string& name,
                                   const FilePath& path);
   void ProcessMediaDeviceDetached(const DeviceIdType& id);
 
+  // Enters or leaves a period of time with a given |requirement|. If the
+  // operation has multiple requirements, make sure to use a unique |reason| for
+  // each one. Reusing the same |reason| is OK as far as the |requirement| is
+  // the same in every call, and each BeginPowerRequirement call is paired with
+  // a call to EndPowerRequirement. |reason| is expected to be an ASCII string.
+  // Must be called from the thread that created the SystemMonitor.
+  // Warning: Please remember that sleep deprivation is not a good thing; use
+  // with caution.
+  void BeginPowerRequirement(PowerRequirement requirement,
+                             const std::string& reason);
+  void EndPowerRequirement(PowerRequirement requirement,
+                           const std::string& reason);
+
+  // Returns the number of outsanding power requirement requests.
+  size_t GetPowerRequirementsCountForTest() const;
+
  private:
 #if defined(OS_MACOSX)
   void PlatformInit();
   void PlatformDestroy();
 #endif
 
   // Platform-specific method to check whether the system is currently
   // running on battery power.  Returns true if running on batteries,
   // false otherwise.
   bool IsBatteryPower();
@@ skipping 11 matching lines @@
   void NotifyPowerStateChange();
   void NotifySuspend();
   void NotifyResume();
 
   scoped_refptr<ObserverListThreadSafe<PowerObserver> > power_observer_list_;
   scoped_refptr<ObserverListThreadSafe<DevicesChangedObserver> >
       devices_changed_observer_list_;
   bool battery_in_use_;
   bool suspended_;
 
+#if defined(OS_WIN)
+  std::map<std::string, std::pair<HANDLE, int> > handles_;
+  base::ThreadChecker thread_checker_;
+#endif
+
 #if defined(ENABLE_BATTERY_MONITORING)
   base::OneShotTimer<SystemMonitor> delayed_battery_check_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(SystemMonitor);
 };
 
 }  // namespace base
 
 #endif  // BASE_SYSTEM_MONITOR_SYSTEM_MONITOR_H_