Download autocheckout whitelist and enable autocheckout for whitelisted sites only.

chrome/browser/autofill/autofill_manager.h

Index: chrome/browser/autofill/autofill_manager.h
diff --git a/chrome/browser/autofill/autofill_manager.h b/chrome/browser/autofill/autofill_manager.h
index 69ba0dc366121deb2c0365ac6f68923220661144..a27d7852adb3f1618ac267b5947b4aca50240523 100644
--- a/chrome/browser/autofill/autofill_manager.h
+++ b/chrome/browser/autofill/autofill_manager.h
@@ -274,6 +274,9 @@ class AutofillManager : public content::WebContentsObserver,
   // Autocheckout flow.
   void OnClickFailed(autofill::AutocheckoutStatus status);
 
+  // Returns the matched whitelist URL prefix for the current tab's url.
+  std::string GetAutocheckoutURLPrefix() const;
+
   // Fills |host| with the RenderViewHost for this tab.
   // Returns false if Autofill is disabled or if the host is unavailable.
   bool GetHost(content::RenderViewHost** host) const WARN_UNUSED_RESULT;