[Autofill] Adding strings for cards from account

This CL lands strings for upcoming changes to the dropdown which will
better reflect the source of users' cards.

See also (googlers only):
https://docs.google.com/document/d/18oV-_0QfoWM7rgp-suzDn4WspFNHRPKxI-4epHDQZIg/edit?usp=sharing

Tbr: ftirelo@chromium.org
Bug: 908543
Change-Id: Idec6a806747ad0b49a41bbe4dc4493b13c67604e
Reviewed-on: https://chromium-review.googlesource.com/c/1351498Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611128}

components/autofill_strings.grdp

@@ -168,6 +168,10 @@
   </message>
   </if>
 
+  <message name="IDS_AUTOFILL_SHOW_ACCOUNT_CARDS" desc="Text shown as an option in the Autofill dropdown. Imperative. When clicked, additional payment cards (e.g., credit/debit cards) that were previously saved in the user's Google Account will be added to the list of suggestions being displayed.">
+    Show cards from your Google Account
+  </message>
+
   <!-- Autofill Credit Card Assisted Filling Infobar -->
   <if expr="is_android">
     <message name="IDS_AUTOFILL_CREDIT_CARD_FILLING_INFOBAR_TITLE" desc="Title text for the Autofill Credit Card Assisted Filling Infobar">