chrome.audio API: treat mute as system wide property

extensions/common/api/audio.idl

Index: extensions/common/api/audio.idl
diff --git a/extensions/common/api/audio.idl b/extensions/common/api/audio.idl
index 36a1124bd3b66b81339248e984c368cb6b9e5885..ac14fa4dae7d34cef1bc260d43e86beaee7711d3 100644
--- a/extensions/common/api/audio.idl
+++ b/extensions/common/api/audio.idl
@@ -7,6 +7,12 @@
 // 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;
@@ -36,8 +42,10 @@ namespace audio {
   dictionary AudioDeviceInfo {
     // The unique identifier of the audio device.
     DOMString id;
+    // Stream type associated with this device (input or output).
+    StreamType streamType;

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

Changing the existing protocol might break the old client. Have you tested if
this will still be compatible with the old client?

[tbarzic, 2017/01/11 00:47:03]

this one should be backward compatible - it's only used when the object is
returned from system - it should be safe to add a new property.

(and also, the event reporting this object does not seem to be utilized)

     // 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".
@@ -58,7 +66,7 @@ namespace audio {
 
   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;
@@ -67,31 +75,54 @@ namespace audio {
     double? gain;
   };
 
+  dictionary MuteChangedEvent {
+    // 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 state 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.

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

No need to indent 4 spaces in the above line.

[tbarzic, 2017/01/11 00:47:03]

Done.

+    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.
@@ -103,9 +134,9 @@ namespace audio {
     static void OnLevelChanged(DOMString id, long level);
 
     // 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.
-    static void OnMuteChanged(boolean isInput, boolean isMuted);
+    // Note that mute state is system-wide and the new value applies to every
+    // audio device with specified stream type.
+    static void onMuteChanged(MuteChangedEvent event);

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

This changed the existing event's protocol. This may break the existing client.

[tbarzic, 2017/01/11 00:47:03]

yes, that comes back to the question for which mnilsson is cc'ed :)
If the event isn't really in use, there's nothing to break, if it is, I'll add
(and mark deprecated) the old event.

 
     // Fired when audio devices change, either new devices being added, or
     // existing devices being removed.