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) {
-      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) {
-      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) {
-      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;

[James Hawkins, 2011/05/31 16:38:16]

I really agree that using a separate global var for this is not ideal.  How
about setting imeui to null here and all of the existing checks should suffice? 
Yes, you may attempt to register inputUI in experimental again, but that should
be harmless.

+    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();
   }
 }