[PaymentReqeust] Add error message in PaymentDetails. (in blink side)

third_party/WebKit/Source/modules/payments/PaymentsValidators.cpp

Index: third_party/WebKit/Source/modules/payments/PaymentsValidators.cpp
diff --git a/third_party/WebKit/Source/modules/payments/PaymentsValidators.cpp b/third_party/WebKit/Source/modules/payments/PaymentsValidators.cpp
index 5fe6dd2cd91e9b298c9c2da680fdb89e1cdb10fb..8d664b5a3c918cd89a341ef884f1330577ab34b1 100644
--- a/third_party/WebKit/Source/modules/payments/PaymentsValidators.cpp
+++ b/third_party/WebKit/Source/modules/payments/PaymentsValidators.cpp
@@ -9,12 +9,12 @@
 
 namespace blink {
 
-// We limit the maximum length of the currency code to 2048 bytes for security reasons.
-static const int maxCurrencyCodeLength = 2048;
+// We limit the maximum length of string to 2048 bytes for security reasons.
+static const int maxiumStringLength = 2048;
 
 bool PaymentsValidators::isValidCurrencyCodeFormat(const String& code, String* optionalErrorMessage)
 {
-    if (code.length() <= maxCurrencyCodeLength)
+    if (code.length() <= maxiumStringLength)
         return true;
 
     if (optionalErrorMessage)
@@ -88,4 +88,15 @@ bool PaymentsValidators::isValidShippingAddress(const mojom::blink::PaymentAddre
     return true;
 }
 
+bool PaymentsValidators::isValidErrorMsgFormat(const String& error, String* optionalErrorMessage)
+{
+    if (error.length() <= maxiumStringLength)
+        return true;
+
+    if (optionalErrorMessage)
+        *optionalErrorMessage = "Error message should be at most 2048 characters long";
+
+    return false;
+}
+
 } // namespace blink