Plumb listenerIDs correctly for events that clobber chrome.Event.prototype.dispatch.

chrome/renderer/resources/extensions/input.ime_custom_bindings.js

 // Copyright (c) 2012 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.
 
 // Custom bindings for the input ime API. Only injected into the
 // v8 contexts for extensions which have permission for the API.
 
 var chromeHidden = requireNative('chrome_hidden').GetChromeHidden();
 
 chromeHidden.registerCustomHook('input.ime', function() {
-  chrome.input.ime.onKeyEvent.dispatch = function(engineID, keyData) {
-    var args = Array.prototype.slice.call(arguments);
-    if (this.validate_) {
-      var validationErrors = this.validate_(args);
-      if (validationErrors) {
-        chrome.input.ime.eventHandled(requestId, false);
-        return validationErrors;
-      }
+  chrome.input.ime.onKeyEvent.dispatchToListener = function(callback, args) {
+    var engineID = args[0];
+    var keyData = args[1];
+
+    var result = false;
+    try {
+      result = chrome.Event.prototype.dispatchToListener(callback, args);
+    } catch (e) {
+      console.error('Error in event handler for onKeyEvent: ' + e.stack);
     }
-    if (this.listeners_.length > 1) {
-      console.error('Too many listeners for onKeyEvent: ' + e.stack);
-      chrome.input.ime.eventHandled(requestId, false);
-      return;
-    }
-    for (var i = 0; i < this.listeners_.length; i++) {
-      try {
-        var requestId = keyData.requestId;
-        var result = this.listeners_[i].callback.apply(null, args);
-        chrome.input.ime.eventHandled(requestId, result);
-      } catch (e) {
-        console.error('Error in event handler for onKeyEvent: ' + e.stack);
-        chrome.input.ime.eventHandled(requestId, false);
-      }
-    }
+    chrome.input.ime.eventHandled(keyData.requestId, result);
   };
 });