Add messages on assertions.

chrome/browser/resources/hotword/state_manager.js

 // Copyright (c) 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.
 
 cr.define('hotword', function() {
   'use strict';
 
   /**
    * Class to manage hotwording state. Starts/stops the hotword detector based
    * on user settings, session requests, and any other factors that play into
@@ skipping 157 matching lines @@
         this.startRecognizer_();
       }
     },
 
     /**
      * Start the recognizer plugin. Assumes the plugin has been loaded and is
      * ready to start.
      * @private
      */
     startRecognizer_: function() {
-      assert(this.pluginManager_);
+      assert(this.pluginManager_, 'No NaCl plugin loaded');
       if (this.state_ != State_.RUNNING) {
         this.state_ = State_.RUNNING;
         this.pluginManager_.startRecognizer();
       }
       if (this.sessionStartedCb_) {
         this.sessionStartedCb_();
         this.sessionStartedCb_ = null;
       }
     },
 
@@ skipping 18 matching lines @@
     },
 
     /**
      * Handle the hotword plugin being ready to start.
      * @private
      */
     onReady_: function() {
       if (this.state_ != State_.STARTING) {
         // At this point, we should not be in the RUNNING state. Doing so would
         // imply the hotword detector was started without being ready.
-        assert(this.state_ != State_.RUNNING);
+        assert(this.state_ != State_.RUNNING, 'Unexpected RUNNING state');
         this.shutdownPluginManager_();
         return;
       }
       this.startRecognizer_();
     },
 
     /**
      * Handle an error from the hotword plugin.
      * @private
      */
     onError_: function() {
       this.state_ = State_.ERROR;
       this.shutdownPluginManager_();
     },
 
     /**
      * Handle hotword triggering.
      * @private
      */
     onTrigger_: function() {
       hotword.debug('Hotword triggered!');
-      assert(this.pluginManager_);
+      assert(this.pluginManager_, 'No NaCl plugin loaded on trigger');
       // Detector implicitly stops when the hotword is detected.
       this.state_ = State_.STOPPED;
 
       // Play the chime.
       this.chime_.play();
 
       chrome.hotwordPrivate.notifyHotwordRecognition('search', function() {});
 
       // Implicitly clear the session. A session needs to be started in order to
       // restart the detector.
@@ skipping 25 matching lines @@
       this.sessionSource_ = null;
       this.sessionStartedCb_ = null;
       this.updateStateFromStatus_();
     }
   };
 
   return {
     StateManager: StateManager
   };
 });