chrome.audio API: treat mute as system wide property

extensions/common/api/audio.idl

 // Copyright (c) 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.
 
 // The <code>chrome.audio</code> API is provided to allow users to
 // get information about and control the audio devices attached to the
 // system. This API is currently only implemented for ChromeOS.
 namespace audio {
 
+  // Type of stream an audio device provides.
+  enum StreamType {
+    INPUT,
+    OUTPUT
+  };
+
   dictionary OutputDeviceInfo {
     // The unique identifier of the audio output device.
     DOMString id;
     // The user-friendly name (e.g. "Bose Amplifier").
     DOMString name;
     // True if this is the current active device.
     boolean isActive;
     // True if this is muted.
     boolean isMuted;
     // The output volume ranging from 0.0 to 100.0.
     double volume;
   };
 
   dictionary InputDeviceInfo {
     // The unique identifier of the audio input device.
     DOMString id;
     // The user-friendly name (e.g. "USB Microphone").
     DOMString name;
     // True if this is the current active device.
     boolean isActive;
     // True if this is muted.
     boolean isMuted;
     // The input gain ranging from 0.0 to 100.0.
     double gain;
   };
 
   dictionary AudioDeviceInfo {
     // The unique identifier of the audio device.
     DOMString id;
+    // Stream type associated with this device (input or output).
+    StreamType streamType;
     // True for input device; false for output device.
-    boolean isInput;
+    [deprecated="Use |streamType|."] boolean isInput;
     // Type of the device, including "INTERNAL_SPEAKER", "INTERNAL_MIC",
     // "HEADPHONE", "USB", "BLUETOOTH", "HDMI", "MIC", "KEYBOARD_MIC",
     // "AOKR", and "OTHER".
     DOMString deviceType;
     // The user-friendly name (e.g. "USB Microphone").
     DOMString displayName;
     // Device name.
     DOMString deviceName;
     // True if this is the current active device.
     boolean isActive;
     // True if this is muted.
     boolean isMuted;
     // The sound level of the device, volume for output, gain for input.
     long level;
     // The stable/persisted device id string when available.
     DOMString? stableDeviceId;
   };
 
   dictionary DeviceProperties {
     // True if this is muted.
-    boolean isMuted;
+    [deprecated="Use $(ref:setMute) to set mute state."] boolean? isMuted;
     // If this is an output device then this field indicates the output volume.
     // If this is an input device then this field is ignored.
     double? volume;
     // If this is an input device then this field indicates the input gain.
     // If this is an output device then this field is ignored.
     double? gain;
   };
 
+  dictionary MuteStateChangedEvent {
+    // Type of the stream for which mute value has changed. The updated mute
+    // value applies to all devices with this stream type.
+    StreamType streamType;
+
+    // Value to which mute steate changed.
+    boolean value;
+  };
+
   callback GetInfoCallback = void(OutputDeviceInfo[] outputInfo,
                                   InputDeviceInfo[] inputInfo);
-  callback SetActiveDevicesCallback = void();
-  callback SetPropertiesCallback = void();
+  callback GetMuteCallback = void(boolean value);
+  callback EmptyCallback = void();
 
   interface Functions {
     // Gets the information of all audio output and input devices.
     static void getInfo(GetInfoCallback callback);
 
-  // Sets the active devices to the devices specified by |ids|.
-  // It can pass in the "complete" active device id list of either input
-  // devices, or output devices, or both. If only input device ids are passed
-  // in, it will only change the input devices' active status, output devices will
-  // NOT be changed; similarly for the case if only output devices are passed.
-  // If the devices specified in |new_active_ids| are already active, they will
-  // remain active. Otherwise, the old active devices will be de-activated
-  // before we activate the new devices with the same type(input/output).
-    static void setActiveDevices(DOMString[] ids,
-                                 SetActiveDevicesCallback callback);
+    // Sets the active devices to the devices specified by |ids|.
+    // It can pass in the "complete" active device id list of either input
+    // devices, or output devices, or both. If only input device ids are passed
+    // in, it will only change the input devices' active status, output devices
+    // will NOT be changed; similarly for the case if only output devices are
+    // passed. If the devices specified in |new_active_ids| are already active,
+    // they will remain active. Otherwise, the old active devices will be
+    // de-activated before we activate the new devices with the same
+    // type(input/output).
+    static void setActiveDevices(DOMString[] ids, EmptyCallback callback);
 
     // Sets the properties for the input or output device.
     static void setProperties(DOMString id,
                               DeviceProperties properties,
-                              SetPropertiesCallback callback);
-     };
+                              EmptyCallback callback);
+
+    // Gets system-wide mute state for the specified stream type.
+    // |streamType|: Stream type for which mute state should be fetched.
+    // |callback|: Callback reporting whether mute is set or not for specified
+    //     stream type.
+    static void getMute(StreamType streamType, GetMuteCallback callback);
+
+    // Sets mute state for a stream type. The mute state will apply to all audio
+    // devices with the specified audio stream type.
+    // |streamType|: Stream type for which mute status should be set.
+    // |value|: New mute value.
+    static void setMute(StreamType streamType,
+                        boolean value,
+                        EmptyCallback callback);
+  };
 
   interface Events {
     // Fired when anything changes to the audio device configuration.
     static void onDeviceChanged();
 
     // Fired when sound level changes for an active audio device.
     // |id|: id of the audio device.
     // |level|: new sound level of device(volume for output, gain for input).
     static void OnLevelChanged(DOMString id, long level);
 
     // Fired when the mute state of the audio input or output changes.
+    // Note that mute state is system-wide and the new value applies to every
+    // audio device with specified stream type.
+    static void onMuteStateChanged(MuteStateChangedEvent event);
+
+    // Fired when the mute state of the audio input or output changes.
     // |isInput|: true indicating audio input; false indicating audio output.
     // |isMuted|: new value of mute state.
+    [deprecated="Use $(ref:onMuteStateChanged)."]

[tbarzic, 2016/12/22 01:29:56]

Do you know if this one is used at all - it doesn't seem to be according to
Chrome UMA?

[jennyz, 2017/01/10 00:47:53]

Better ask mnilsson.

     static void OnMuteChanged(boolean isInput, boolean isMuted);
 
     // Fired when audio devices change, either new devices being added, or
     // existing devices being removed.
     // |devices|: List of all present audio devices after the change.
     static void OnDevicesChanged(AudioDeviceInfo[] devices);
   };
 };