Add the ability to filter out extension IMEs from the language settings page.

chrome/browser/resources/options/language_options.html

 <div id="languagePage" class="page" hidden>
   <div class="close-button"></div>
   <h1 i18n-content="languagePage"></h1>
   <div class="content-area">
     <div id="notification">
       <span>&nbsp;</span>
       <span class="link"><span class="link-color"></span></span>
     </div>
     <!-- TODO(kevers): Fix format of i18n-content labels -->
     <div class="language-options-header">
       <div i18n-content="add_language_instructions"></div>
 <if expr="pp_ifdef('chromeos')">
       <div i18n-content="input_method_instructions"></div>
 </if>
     </div>
     <div class="language-options">
       <div class="language-options-left">
         <h3 i18n-content="languages"></h3>
         <list id="language-options-list"></list>
         <div class="language-options-lower-left">
           <button id="language-options-add-button"
                   i18n-content="add_button"></button>

[James Hawkins, 2012/09/12 16:11:58]

nit while you're here: Wrapped element lines should be indented 4 spaces only
(not aligned on attribute name).

[Zachary Kuznia, 2012/09/13 09:28:32]

Done.

+<if expr="pp_ifdef('chromeos')">
+          <button id="language-options-extension-ime-button"
+                  i18n-content="extension_ime_label"></button>
+</if>
         </div>
         <div id="language-options-list-dropmarker"></div>
       </div>
 <!-- Chrome uses the native OS spellchecker in OS X, so don't display the
      dictionary pane. -->
 <if expr="not is_macosx">
       <div class="language-options-right">
         <h3 id="language-options-language-name"></h3>
 <if expr="os == 'win32' or pp_ifdef('chromeos')">
         <div class="language-options-contents">
@@ skipping 61 matching lines @@
       </div>
 </if>
     </div>
   </div>
   <div class="action-area">
     <div class="button-strip">
       <button id="language-confirm" i18n-content="ok"></button>
     </div>
   </div>
 </div>