Initial implementation of the credit card assisted filling infobar.

On page load, this will prompt the user for automatic credit card filling. When user accepts the prompt, the credit card form is filled with their credit card data.

Several big TODOs:
* Opening a dialog to get the CVC (hoping to reuse PaymentRequest code)
* Only proposing the assist when the form is in the viewport.
* Offering more than 1 card in the infobar.

Mocks (internal): https://folio.googleplex.com/chrome-ux/mocks/304-payments-zero-integration/ZI_V2_Exploration/autofill-ahead-infobar#%2F06.png%3Fc=show

Video (public): https://drive.google.com/file/d/0B3xzZ-vFr2LRMW1yUkZDYWR4Um8/view?usp=sharing

BUG=630656
TEST=AssistManagerTest,AutofillCreditCardFillingInfoBarDelegateMobileTest

Review-Url: https://codereview.chromium.org/2026353002
Cr-Commit-Position: refs/heads/master@{#409841}
diff --git a/components/components_strings.grd b/components/components_strings.grd
index bd5901b..8e1adc5 100644
--- a/components/components_strings.grd
+++ b/components/components_strings.grd
@@ -227,6 +227,9 @@
       <message name="IDS_OK" desc="Used for OK on buttons">
         OK
       </message>
+      <message name="IDS_NO_THANKS" desc="Used to dismiss various prompts.">
+        No thanks
+      </message>
       <if expr="not use_titlecase">
         <message name="IDS_NOT_NOW" desc="Used on a button that avoids taking a suggested action.  The action will likely be suggested again or automatically taken later.">
           Not now