Add credit card scanner to payments UI.

The credit card scanner UI is behind the
chrome://flags#scan-cards-in-web-payments flag until UI behavior is
polished.

BUG=640430

Review-Url: https://codereview.chromium.org/2286563002
Cr-Commit-Position: refs/heads/master@{#417709}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index d3d02da..d26df12ae 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -2020,6 +2020,10 @@
      IDS_FLAGS_ENABLE_ANDROID_PAY_INTEGRATION_V1_NAME,
      IDS_FLAGS_ENABLE_ANDROID_PAY_INTEGRATION_V1_DESCRIPTION, kOsAndroid,
      FEATURE_VALUE_TYPE(chrome::android::kAndroidPayIntegrationV1)},
+    {"scan-cards-in-web-payments",
+     IDS_FLAGS_SCAN_CARDS_IN_WEB_PAYMENTS_NAME,
+     IDS_FLAGS_SCAN_CARDS_IN_WEB_PAYMENTS_DESCRIPTION, kOsAndroid,
+     FEATURE_VALUE_TYPE(chrome::android::kScanCardsInWebPayments)},
 #endif
 #if defined(OS_CHROMEOS)
     {"disable-eol-notification", IDS_FLAGS_EOL_NOTIFICATION_NAME,