CrOS - Add strings for PIN input field

Add a11y string for the upcoming PIN field on the
login screen.

Bug: 1075994
Change-Id: I239add7de17c464191e6b0294e58f615e8a90945
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2349868
Auto-Submit: Renato Silva <rrsilva@google.com>
Reviewed-by: Denis Kuznetsov [CET] <antrim@chromium.org>
Commit-Queue: Renato Silva <rrsilva@google.com>
Cr-Commit-Position: refs/heads/master@{#797199}

ash/ash_strings.grd

@@ -1961,6 +1961,9 @@ This file contains the strings for ash.
       <message name="IDS_ASH_LOGIN_POD_PASSWORD_PIN_PLACEHOLDER" desc="Text to display as placeholder in the password field when both password and pin are allowed.">
         PIN or password
       </message>
+      <message name="IDS_ASH_LOGIN_POD_PASSWORD_PIN_INPUT_ACCESSIBLE_NAME" desc="The accessible name of the pin input field used for PIN Auto-submit">
+        Enter your PIN
+      </message>
       <message name="IDS_ASH_LOGIN_SWITCH_TO_PASSWORD" desc="Text to display on the button that is used for switching between PIN and password authentication">
         Switch to password
       </message>

ash/ash_strings_grd/IDS_ASH_LOGIN_POD_PASSWORD_PIN_INPUT_ACCESSIBLE_NAME.png.sha1

+3f38905d613f3ce7c8e07d79d91bf6a7d89336f1
\ No newline at end of file