[Payments] Basic validation in the credit card editor.

components/autofill/core/browser/validation.h

Index: components/autofill/core/browser/validation.h
diff --git a/components/autofill/core/browser/validation.h b/components/autofill/core/browser/validation.h
index a09ae75cbb3af7470832ce8306dcfdf34f1d8639..88db88bbc35fae6808cb92c30ed199e2a1538e28 100644
--- a/components/autofill/core/browser/validation.h
+++ b/components/autofill/core/browser/validation.h
@@ -7,6 +7,7 @@
 
 #include "base/strings/string16.h"
 #include "base/strings/string_piece.h"
+#include "components/autofill/core/browser/field_types.h"
 
 namespace base {
 class Time;
@@ -43,6 +44,12 @@ bool IsValidZip(const base::string16& text);
 // Returns true if |text| looks like an SSN, with or without separators.
 bool IsSSN(const base::string16& text);
 
+// Returns whether |value| is valid for the given |type|. If not null,
+// |error_message| is populated when the function returns false.
+bool IsValidForType(const base::string16& value,
+                    ServerFieldType type,
+                    base::string16* error_message);
+
 }  // namespace autofill
 
 #endif  // COMPONENTS_AUTOFILL_CORE_BROWSER_VALIDATION_H_