Stop ChromeVox Next page loading sounds when page finishes loading.

chrome/browser/resources/chromeos/chromevox/cvox2/background/earcon_engine.js

 // Copyright 2015 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.
 
 /**
  * @fileoverview This is the low-level class that generates ChromeVox's
  * earcons. It's designed to be self-contained and not depend on the
  * rest of the code.
  */
 
@@ skipping 667 matching lines @@
     removeCount++;
   }
   this.progressSources_.splice(0, removeCount);
 };
 
 /**
  * Start playing tick / tock progress sounds continuously until
  * explicitly canceled.
  */
 EarconEngine.prototype.startProgress = function() {
+  if (this.progressIntervalID_) {
+    this.cancelProgress();
+  }
+
   this.progressSources_ = [];
   this.progressGain_ = 0.5;
   this.progressTime_ = this.context_.currentTime;
   this.generateProgressTickTocks_();
   this.progressIntervalID_ = window.setInterval(
       this.generateProgressTickTocks_.bind(this), 1000);
 };
 
 /**
  * Stop playing any tick / tock progress sounds.
  */
 EarconEngine.prototype.cancelProgress = function() {
   if (!this.progressIntervalID_) {
     return;
   }
 
   for (var i = 0; i < this.progressSources_.length; i++) {
     this.progressSources_[i][1].stop();
   }
   this.progressSources_ = [];
 
   window.clearInterval(this.progressIntervalID_);
   this.progressIntervalID_ = null;
 };