Add contentDescription to offline badges on the NTP

chrome/android/java/strings/android_chrome_strings.grd

Index: chrome/android/java/strings/android_chrome_strings.grd
diff --git a/chrome/android/java/strings/android_chrome_strings.grd b/chrome/android/java/strings/android_chrome_strings.grd
index 9de25da0a2c129cd8f64ef1f19a39cb97e83257e..adfe0412efd955b1a4eb3cee0d42f491e1b768c7 100644
--- a/chrome/android/java/strings/android_chrome_strings.grd
+++ b/chrome/android/java/strings/android_chrome_strings.grd
@@ -1947,6 +1947,9 @@ To obtain new licenses, connect to the internet and play your downloaded content
       <message name="IDS_NTP_STATUS_CARD_BODY_EMPTY" desc="Body of the card explaining the status of the ntp suggested content, when we don't have anything to show.">
         More cards will appear when the time is right.
       </message>
+      <message name="IDS_ACCESSIBILITY_NTP_OFFLINE_BADGE" desc="Content description for the badge that indicates offline availability of a most visited item on the new tab page.">
+        Available offline
+      </message>
 
       <!-- Toolbar button strings -->
       <message name="IDS_OPEN_TABS" desc="Text for button to enter the tab switcher and show tabs that are open on this device">