media/base/output_device.h

   1 // Copyright (c) 2015 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 MEDIA_BASE_OUTPUT_DEVICE_H_
   6 #define MEDIA_BASE_OUTPUT_DEVICE_H_
   7
   8 #include <string>
   9
  10 #include "base/callback.h"
  11 #include "media/audio/audio_parameters.h"
  12 #include "media/base/media_export.h"
  13 #include "url/gurl.h"
  14
  15 namespace media {
  16
  17 // Result of an audio output device switch operation
  18 enum SwitchOutputDeviceResult {
  19   SWITCH_OUTPUT_DEVICE_RESULT_SUCCESS = 0,
  20   SWITCH_OUTPUT_DEVICE_RESULT_ERROR_NOT_FOUND,
  21   SWITCH_OUTPUT_DEVICE_RESULT_ERROR_NOT_AUTHORIZED,
  22   SWITCH_OUTPUT_DEVICE_RESULT_ERROR_OBSOLETE,
  23   SWITCH_OUTPUT_DEVICE_RESULT_ERROR_NOT_SUPPORTED,
  24   SWITCH_OUTPUT_DEVICE_RESULT_LAST =
  25       SWITCH_OUTPUT_DEVICE_RESULT_ERROR_NOT_SUPPORTED,
  26 };
  27
  28 typedef base::Callback<void(SwitchOutputDeviceResult)> SwitchOutputDeviceCB;
  29
  30 // OutputDevice is an interface that allows performing operations related
  31 // audio output devices.
  32
  33 class OutputDevice {
  34  public:
  35   // Attempts to switch the audio output device.
  36   // Once the attempt is finished, |callback| is invoked with the
  37   // result of the operation passed as a parameter. The result is a value from
  38   // the  media::SwitchOutputDeviceResult enum.
  39   // There is no guarantee about the thread where |callback| will
  40   // be invoked, so users are advised to use media::BindToCurrentLoop() to
  41   // ensure that |callback| runs on the correct thread.
  42   // Note also that copy constructors and destructors for arguments bound to
  43   // |callback| may run on arbitrary threads as |callback| is moved across
  44   // threads. It is advisable to bind arguments such that they are released by
  45   // |callback| when it runs in order to avoid surprises.
  46   virtual void SwitchOutputDevice(const std::string& device_id,
  47                                   const GURL& security_origin,
  48                                   const SwitchOutputDeviceCB& callback) = 0;
  49
  50  protected:
  51   virtual ~OutputDevice() {}
  52 };
  53
  54 }  // namespace media
  55
  56 #endif  // MEDIA_BASE_OUTPUT_DEVICE_H_