Update AX role mapping for summary to AXButton on Mac

content/app/strings/content_strings.grd

Index: content/app/strings/content_strings.grd
diff --git a/content/app/strings/content_strings.grd b/content/app/strings/content_strings.grd
index 8b521fcbf1cd386a40eda3c0e38b7151a198282b..5bced3b8384813f6cdcefc5504be8294f6fe828c 100644
--- a/content/app/strings/content_strings.grd
+++ b/content/app/strings/content_strings.grd
@@ -294,6 +294,9 @@ below:
       <message name="IDS_AX_ROLE_DESCRIPTION_TERM" desc="Accessibility role description for description term (as in a description list)">
         term
       </message>
+      <message name="IDS_AX_ROLE_DISCLOSURE_TRIANGLE" desc="Accessibility role description for a disclosure triangle, a control shaped like a triangle that expands or collapses to show or hide extra content">
+        disclosure triangle
+      </message>
       <message name="IDS_AX_ROLE_FEED" desc="Accessibility role description for a scrollable list of articles.">
         feed
       </message>
@@ -402,9 +405,6 @@ below:
         <message name="IDS_AX_ROLE_DIRECTORY" desc="Accessibility role description for a directory, for example a table of contents or list of employees">
           directory
         </message>
-        <message name="IDS_AX_ROLE_DISCLOSURE_TRIANGLE" desc="Accessibility role description for a disclosure triangle, a control shaped like a triangle that expands or collapses to show or hide extra content">
-          disclosure triangle
-        </message>
         <message name="IDS_AX_ROLE_DOCUMENT" desc="Accessibility role description for a document">
           document
         </message>