Only allow extension pages to be displayed in the sidebar to be consistent...

chrome/app/generated_resources.grd

 <?xml version="1.0" encoding="UTF-8"?>
 
 <!-- This file contains definitions of resources that will be translated for
 each locale. -->
 
 <grit base_dir="." latest_public_release="0" current_release="1"
       source_lang_id="en" enc_check="möl">
   <outputs>
     <output filename="grit/generated_resources.h" type="rc_header">
       <emit emit_type='prepend'></emit>
@@ skipping 3603 matching lines @@
       </message>
       <message name="IDS_EXTENSION_LOAD_ICON_FOR_BROWSER_ACTION_FAILED" desc="">
         Could not load icon '<ph name="ICON">$1<ex>icon.png</ex></ph>' for browser action.
       </message>
       <message name="IDS_EXTENSION_LOAD_BACKGROUND_PAGE_FAILED" desc="">
         Could not load background page '<ph name="BACKGROUND_PAGE">$1<ex>page.html</ex></ph>'.
       </message>
       <message name="IDS_EXTENSION_LOAD_OPTIONS_PAGE_FAILED" desc="">
         Could not load options page '<ph name="OPTIONS_PAGE">$1<ex>page.html</ex></ph>'.
       </message>
+      <message name="IDS_EXTENSION_LOAD_SIDEBAR_PAGE_FAILED" desc="">
+        Could not load sidebar page '<ph name="SIDEBAR_PAGE">$1<ex>page.html</ex></ph>'.
+      </message>
       <if expr="os == 'win32'">
         <message name="IDS_EXTENSION_UNPACK_FAILED" desc="On windows, it is possible to mount a disk without the root of that disk having a drive letter.  The sandbox does not support this. See crbug/49530 .">
           Can not unpack extension.  To safely unpack an extension, there must be a path to your profile directory that starts with a drive letter and does not contain a junction, mount point, or symlink.  No such path exists for your profile.
         </message>
       </if>
       <if expr="os != 'win32'">
         <message name="IDS_EXTENSION_UNPACK_FAILED" desc="">
           Can not unpack extension.  To safely unpack an extension, there must be a path to your profile directory that does not contain a symlink.  No such path exists for your profile.
         </message>
       </if>
@@ skipping 7521 matching lines @@
     </includes>
     <structures fallback_to_english="true">
       <structure name="IDD_CHROME_FRAME_FIND_DIALOG" file="cf_resources.rc" type="dialog" >
       </structure>
       <structure name="IDD_CHROME_FRAME_READY_PROMPT" file="cf_resources.rc" type="dialog" >
       </structure>
     </structures>
 
   </release>
 </grit>