Debugging for https://crbug.com/601435.

extensions/renderer/resources/serial_service.js

 // 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.
 
 define('serial_service', [
     'content/public/renderer/frame_service_registry',
     'data_receiver',
     'data_sender',
     'device/serial/serial.mojom',
     'device/serial/serial_serialization.mojom',
@@ skipping 267 matching lines @@
     if ($Object.keys(serviceOptions).length == 0)
       return true;
     return this.remoteConnection_.setOptions(serviceOptions).then(
         function(result) {
       return !!result.success;
     }).catch(function() {
       return false;
     });
   };
 
+  var calls = 0;
   Connection.prototype.getControlSignals = function() {
+    // Creating this on any earlier call causes the handles to be lost and not
+    // cleaned up.
+    if (calls++ == 7) {
+      var pipe = core.createMessagePipe();
+      core.close(pipe.handle1);
+      core.close(pipe.handle0);
+    }
     return this.remoteConnection_.getControlSignals().then(function(result) {
       if (!result.signals)
         throw new Error('Failed to get control signals.');
       var signals = result.signals;
       return {
         dcd: !!signals.dcd,
         cts: !!signals.cts,
         ri: !!signals.ri,
         dsr: !!signals.dsr,
       };
@@ skipping 246 matching lines @@
 
   return {
     getDevices: getDevices,
     createConnection: Connection.create,
     getConnection: getConnection,
     getConnections: getConnections,
     // For testing.
     Connection: Connection,
   };
 });