Media Controls a11y: add text/description/role to more controls components.

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 c72fd5e424e7731c3a083abf61cd9b5de0db52d6..798b109533423d60cdef297e42a7805b5c8ca3c2 100644
--- a/content/app/strings/content_strings.grd
+++ b/content/app/strings/content_strings.grd
@@ -620,6 +620,14 @@ below:
         control remote playback
       </message>
 
+      <message name="IDS_AX_MEDIA_DOWNLOAD_BUTTON" desc="Media controls download button.">
+        download media
+      </message>
+
+      <message name="IDS_AX_MEDIA_OVERFLOW_BUTTON" desc="Media controls overflow button.">
+        show more media controls
+      </message>
+
       <message name="IDS_AX_MEDIA_AUDIO_ELEMENT_HELP" desc="Accessible help of audio controls">
         audio
       </message>
@@ -692,6 +700,10 @@ below:
         control remote playback
       </message>
 
+      <message name="IDS_AX_MEDIA_OVERFLOW_BUTTON_HELP" desc="accessibility help description for overflow button.">
+        more options
+      </message>
+
       <message name="IDS_AX_MILLISECOND_FIELD_TEXT" desc="Accessible description of the millisecond field in a date/time control">
         Milliseconds
       </message>
@@ -852,9 +864,6 @@ below:
         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_AX_MEDIA_OVERFLOW_BUTTON" desc="Media controls overflow menu.">
-        Overflow menu
-      </message>
       <message name="IDS_MEDIA_OVERFLOW_MENU_CLOSED_CAPTIONS" desc="Media controls overflow menu item label for a closed captions button. The text for this overflow menu should be short.">
         Captions
       </message>