Make availability of hotword hardware known to hotword component extension.

chrome/common/extensions/api/hotword_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.
 
 // The <code>chrome.hotwordPrivate</code> API allows extensions to access and
 // mutate the preference for enabling hotword search. It also provides
 // information on whether the hotword search is available. This API provides an
 // event interface to transmit to the extension a signal that the preference fo
 // hotword search has change.
 //
@@ skipping 21 matching lines @@
     boolean experimentalHotwordEnabled;
 
     // Whether always-on hotwording is enabled.
     boolean alwaysOnEnabled;
 
     // Whether training mode is enabled.
     boolean trainingEnabled;
 
     // Whether the user corresponding to this profile is the active user.
     boolean userIsActive;
+
+    // Whether the hotword stream is available if requested.
+    boolean hotwordStreamAvailable;

[kcarattini, 2015/03/17 00:47:15]

Why not call this hotwordHardwareAvailable? That's what it actually checks for.

[Anand Mistry (off Chromium), 2015/03/17 02:54:47]

Done.

   };
 
   dictionary LaunchState {
     // TODO(kcarattini): Consider adding more variables here,
     // such as the available state of the hotword service.
 
     // The mode that the Hotword Audio Verification app was launched in.
     long launchMode;
   };
 
@@ skipping 107 matching lines @@
     // Fired when the speaker model has been saved.
     static void onSpeakerModelSaved();
 
     // Fired when a hotword has triggered.
     static void onHotwordTriggered();
 
     // Fired when the speaker model should be deleted.
     static void onDeleteSpeakerModel();
   };
 };