Fix MSAA+IA2 & AX for <header> tag and banner role

content/app/strings/content_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 
 <!-- This file contains definitions of resources that will be translated for
 each locale. Specifically, these are UI strings that are used by content that
 need to be translated for each locale.-->
 
 <!-- Some of these strings and string descriptions were taken from
 WebKit/win/WebCoreLocalizedStrings.cpp so we include the original license
 below:
 
@@ skipping 317 matching lines @@
       <message name="IDS_AX_CALENDAR_SHOW_NEXT_MONTH" desc="Accessible description of a button to show next month in a calendar picker.">
         Show next month
       </message>
       <message name="IDS_AX_CALENDAR_SHOW_PREVIOUS_MONTH" desc="Accessible description of a button to show previous month in a calendar picker.">
         Show previous month
       </message>
       <message name="IDS_AX_CALENDAR_WEEK_DESCRIPTION" desc="Accessible description of a button to select a specific week.">
         <ph name="WEEK">$1<ex>Week 38, 2014</ex></ph>, starting on <ph name="WEEK_START_DATE">$2<ex>September 15, 2014</ex></ph>
       </message>
 
+      <message name="IDS_AX_ROLE_BANNER" desc="accessibility role description for banner">
+        banner
+      </message>
       <message name="IDS_AX_ROLE_WEB_AREA" desc="accessibility role description for web area">
         HTML content
       </message>
       <message name="IDS_AX_ROLE_LINK" desc="accessibility role description for link">
         link
       </message>
       <message name="IDS_AX_ROLE_LIST_MARKER" desc="accessibility role description for list marker">
         list marker
       </message>
       <message name="IDS_AX_ROLE_IMAGE_MAP" desc="accessibility role description for image map">
@@ skipping 349 matching lines @@
         Please lengthen this text to <ph name="MIN_CHARACTERS">$2<ex>101</ex></ph> characters or more (you are currently using <ph name="CURRENT_LENGTH">$1<ex>100</ex></ph> characters).
       </message>
 
       <message name="IDS_PLUGIN_INITIALIZATION_ERROR" desc="A message displayed when a plug-in failed to load">
         Couldn't load plug-in.
       </message>
 
     </messages>
   </release>
 </grit>