Remove use_name_for_id from ios_strings.grd to unblock translation process.

grd files that are sent off for translation cannot contain the
use_name_for_id attribute as described in the bug. This removes
use_name_for_id from ios_strings.grd to fix the extract strings step.

This will need to be fixed for real as a follow-up, either by making
IDS_IOS_ACCEPT_LANGUAGES and IDS_IOS_DEFAULT_ENCODING regular
translatable strings, or by moving them into a separate file as is done
with all the locale_settings_<platform>.grd files.

BUG=531718
TBR=sdefresne@chromium.org

Review URL: https://codereview.chromium.org/1341533006

Cr-Commit-Position: refs/heads/master@{#348764}

ios/chrome/app/strings/ios_strings.grd

@@ -131,12 +131,12 @@ all other OS specific variables will be false.
   <release seq="1" allow_pseudo="false">
     <messages fallback_to_english="true">
       <!-- The default value for HTTP Accept-Language header. -->
-      <message name="IDS_IOS_ACCEPT_LANGUAGES" use_name_for_id="true">
+      <message name="IDS_IOS_ACCEPT_LANGUAGES" translateable="false">
         en-US,en
       </message>
 
       <!-- The default value for |WebPreference::default_encoding|. -->
-      <message name="IDS_IOS_DEFAULT_ENCODING" use_name_for_id="true">
+      <message name="IDS_IOS_DEFAULT_ENCODING" translateable="false">
         windows-1252
       </message>