content/public/browser/power_save_blocker.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_PUBLIC_BROWSER_POWER_SAVE_BLOCKER_H_
   6 #define CONTENT_PUBLIC_BROWSER_POWER_SAVE_BLOCKER_H_
   7
   8 #include <string>
   9
  10 #include "base/basictypes.h"
  11 #include "base/memory/scoped_ptr.h"
  12 #include "content/common/content_export.h"
  13
  14 namespace content {
  15
  16 // A RAII-style class to block the system from entering low-power (sleep) mode.
  17 // This class is thread-safe; it may be constructed and deleted on any thread.
  18 class CONTENT_EXPORT PowerSaveBlocker {
  19  public:
  20   enum PowerSaveBlockerType {
  21     // Prevent the application from being suspended. On some platforms, apps may
  22     // be suspended when they are not visible to the user. This type of block
  23     // requests that the app continue to run in that case, and on all platforms
  24     // prevents the system from sleeping.
  25     // Example use cases: downloading a file, playing audio.
  26     kPowerSaveBlockPreventAppSuspension,
  27
  28     // Prevent the display from going to sleep. This also has the side effect of
  29     // preventing the system from sleeping, but does not necessarily prevent the
  30     // app from being suspended on some platforms if the user hides it.
  31     // Example use case: playing video.
  32     kPowerSaveBlockPreventDisplaySleep,
  33   };
  34
  35   // Reasons why power-saving features may be blocked.
  36   enum Reason {
  37     // Audio is being played.
  38     kReasonAudioPlayback,
  39     // Video is being played.
  40     kReasonVideoPlayback,
  41     // Power-saving is blocked for some other reason.
  42     kReasonOther,
  43   };
  44
  45   virtual ~PowerSaveBlocker() = 0;
  46
  47   // Pass in the type of power save blocking desired. If multiple types of
  48   // blocking are desired, instantiate one PowerSaveBlocker for each type.
  49   // |reason| and |description| (a more-verbose, human-readable justification of
  50   // the blocking) may be provided to the underlying system APIs on some
  51   // platforms.
  52   static scoped_ptr<PowerSaveBlocker> Create(PowerSaveBlockerType type,
  53                                              Reason reason,
  54                                              const std::string& description);
  55 };
  56
  57 }  // namespace content
  58
  59 #endif  // CONTENT_PUBLIC_BROWSER_POWER_SAVE_BLOCKER_H_