Catch exception when register extension with inputUI.

chrome/browser/resources/keyboard/ime.js

 // Copyright (c) 2011 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 An input method UI implementation
  */
 
 /**
  * Const variables
  */
 const IME_HEIGHT = 48;
 const IME_VMARGIN = 12;
 const IME_HMARGIN = 16;
 const IME_FONTSIZE = IME_HEIGHT - IME_VMARGIN * 2;
 const IME_MAX_CANDIDATES = 20;
 
 /**
+ * global variables
+ */
+var imeEnabled = true;
+
+/**
  * Creates a new button element.
  * @param {Object=} opt_propertyBag Optional properties.
  * @constructor
  * @extends {HTMLButtonElement}
  */
 var Button = cr.ui.define('button');
 
 Button.prototype = {
   __proto__: HTMLButtonElement.prototype,
   /**
@@ skipping 153 matching lines @@
     // TODO(penghuang) Adjust the width of all items in ImeUi to fill the width
     // of keyboard.
   },
 
   /**
    * Candidate is clicked.
    * @param {number} index The index of the candidate.
    * @return {void}
    */
   candidateClicked: function(index) {
-    if (!chrome.experimental) {
+    if (!imeEnabled) {

[James Hawkins, 2011/05/30 22:07:15]

Why is this check necessary since ImeUi is not created if
chrome.experimental.inputUI.register() throws an exception?

[Peng, 2011/05/31 14:55:34]

Done.

Remove all check code

       console.log('candidateClicked(' + index + '): experimental is disabled.');
       return;
     }
     chrome.experimental.inputUI.candidateClicked(index, 1);
   },
 
   /**
    * Go to the previous page of the lookup table.
    * @return {void}
    */
   pageUp: function() {
-    if (!chrome.experimental) {
+    if (!imeEnabled) {
       console.log('pageUp: experimental is disabled.');
       return;
     }
     chrome.experimental.inputUI.pageUp();
   },
 
   /**
    * Go to the next page of the lookup table.
    * @return {void}
    */
   pageDown: function() {
-    if (!chrome.experimental) {
+    if (!imeEnabled) {
       console.log('pageDown: experimental is diabled.');
       return;
     }
     chrome.experimental.inputUI.pageDown();
   },
 };
 
 var imeui = null;
 
 /**
  * Initialize Ime Ui
  * @param {Element} element The html element which will contain the ImeUi.
  * @return {void}
  */
 function initIme(element) {
-  // imeui has been initialized.
-  if (imeui) {
+  if (!imeEnabled || imeui) {
+  // ime is not enabled in chromium or ime ui has been initialized.
     return;
   }
 
+  try {
+    // Register self to receive input method UI events.
+    chrome.experimental.inputUI.register();
+  } catch (e) {
+    // The ime is not enabled in chromium.
+    imeEnabled = false;
+    return;
+  }
+
   imeui = new ImeUi();
 
   element.appendChild(imeui);
 
   // new row
   var clearingDiv = document.createElement('div');
   clearingDiv.style.clear = 'both';
   element.appendChild(clearingDiv);
 
-  if (!chrome.experimental)
-    return;
-
-  // Register self to receive input method UI events.
-  chrome.experimental.inputUI.register();
-
   // Install events handlers.
   chrome.experimental.inputUI.onSetCursorLocation.addListener(
       function(x, y, w, h) {
         imeui.setCursorLocation(x, y, w, h);
       });
   chrome.experimental.inputUI.onUpdateAuxiliaryText.addListener(
       function(text) {
         imeui.updateAuxiliaryText(text);
       });
   chrome.experimental.inputUI.onUpdateLookupTable.addListener(
       function(table) {
         imeui.updateLookupTable(table);
       });
 }
 
 /**
  * Updates Ime Ui. It should be called when window is resized.
  * @return {void}
  */
 function updateIme() {
-  if (imeui) {
+  if (imeEnabled && imeui) {
     imeui.update();
   }
 }