Redesign the copresence audio handlers.

chrome/common/extensions/api/copresence_private.idl

 // Copyright 2014 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.
 
 // Use the <code>chrome.copresencePrivate</code> API to interface with Chrome
 // from the whispernet_proxy extension.
 namespace copresencePrivate {
+  // This is the type of decode request. It specifies which decoders to run on
+  // the given samples.
+  enum DecodeRequestType { audible, inaudible, both };

[not at google - send to devlin, 2014/10/17 20:17:57]

This will only ever be audible/inaudible, right? Because 'both' could easily
become meaningless. I think a better model for this would be an object with
boolean keys audible and inaudible, and not have an enum at all. It doesn't
really feel like an enum.

[rkc, 2014/10/17 21:50:22]

Done.

 
   dictionary PlayParameters {
     double sampleRate;
     long bitsPerSample;
     double carrierFrequency;
     long repetitions;
   };
 
   dictionary RecordParameters {
     double sampleRate;
@@ skipping 22 matching lines @@
     // Send a boolean indicating whether we detected a broadcast or not.
     static void sendDetect(boolean detected);
   };
 
   interface Events {
     // Fired to request initialization of the whisper.net library.
     static void onInitialize(AudioParameters audioParams);
     // Fired to request encoding of the given token.
     static void onEncodeTokenRequest(DOMString base64Token, boolean audible);
     // Fired when we have new samples to decode.
-    static void onDecodeSamplesRequest(ArrayBuffer audioSamples);
+    static void onDecodeSamplesRequest(DecodeRequestType type,

[not at google - send to devlin, 2014/10/17 20:17:57]

This isn't backwards compatible? Not a problem right at this moment given only a
built-in extension uses it, but it's a bad habit to get into.

Either
- put the new argument at the end
- make whole single argument a choice between an object (containing both type
and audioSamples as keys) OR audioSamples, then expect callers to detect.

The former is probably easier, doesn't scale very well obviously, but it's a
private API anyway.

[rkc, 2014/10/17 21:50:22]

Done.

+                                       ArrayBuffer audioSamples);
     // Fired to request a DetectBroadcast.
     static void onDetectBroadcastRequest();
   };
 };