[Autofill] Don't validate China UnionPay cards with the Luhn checksum.

components/autofill/core/browser/validation.cc

Index: components/autofill/core/browser/validation.cc
diff --git a/components/autofill/core/browser/validation.cc b/components/autofill/core/browser/validation.cc
index 9d561f5126919c75b1568e4abca56ba6fde1f84b..a8aef35f7caafa62f9c31b03c238725922745d03 100644
--- a/components/autofill/core/browser/validation.cc
+++ b/components/autofill/core/browser/validation.cc
@@ -78,11 +78,18 @@ bool IsValidCreditCardNumber(const base::string16& text) {
     return false;
   if (type == kMasterCard && number.size() != 16)
     return false;
+  if (type == kUnionPay && (number.size() < 16 || number.size() > 19))
+    return false;
   if (type == kVisaCard && number.size() != 13 && number.size() != 16)
     return false;
   if (type == kGenericCard && (number.size() < 12 || number.size() > 19))
     return false;
 
+  // Unlike all the other supported types, UnionPay cards lack Luhn checksum
+  // validation.
+  if (type == kUnionPay)
+    return true;
+
   // Use the Luhn formula [3] to validate the number.
   // [3] http://en.wikipedia.org/wiki/Luhn_algorithm
   int sum = 0;