[Payments] Auto-advance to next field after typing in valid credit card with maximum digits

chrome/android/java/src/org/chromium/chrome/browser/payments/ui/EditorFieldModel.java

Index: chrome/android/java/src/org/chromium/chrome/browser/payments/ui/EditorFieldModel.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/payments/ui/EditorFieldModel.java b/chrome/android/java/src/org/chromium/chrome/browser/payments/ui/EditorFieldModel.java
index 55c07a030e398875cb9f99ace4e3d505d3b0530c..9ecfb1a93d94641dbd322e5d13aeaaf94a53a693 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/payments/ui/EditorFieldModel.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/payments/ui/EditorFieldModel.java
@@ -34,6 +34,15 @@ public class EditorFieldModel {
          * @return True if the value is valid.
          */
         boolean isValid(@Nullable CharSequence value);
+
+        /**
+         * Called to check whehter the length of the field value is maximum.
+         *
+         * @param value The value of the field to check.
+         * @return True if the field value length is maximum among all the possible valid values in
+         *         this field.
+         */
+        boolean isLengthMaximum(@Nullable CharSequence value);
     }
 
     /**
@@ -499,6 +508,16 @@ public class EditorFieldModel {
     }
 
     /**
+     * Returns true if the field value length is maximum among all the possible valid values in this
+     * field.
+     *
+     * @Return Whether the field value length is maximum.
+     */
+    public boolean isLengthMaximum() {
+        return mValidator == null ? false : mValidator.isLengthMaximum(mValue);
+    }
+
+    /**
      * Sets the dropdown callback.
      *
      * @param callback The callback to invoke when the dropdown selection has changed. The first