[Android NTP] Move more of the dismissal logic into the tree.

chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SignInPromo.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SignInPromo.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SignInPromo.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SignInPromo.java
index e83e92a454d3714484a4e8780ce302e2f5a7b5f9..860248a476565c502118b0c97d3c8afb2caffce7 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SignInPromo.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SignInPromo.java
@@ -114,6 +114,11 @@ public class SignInPromo extends OptionalLeaf
         super.setVisible(!mDismissed && visible);
     }
 
+    @Override
+    protected boolean canBeDismissed() {
+        return true;
+    }
+
     /** Hides the sign in promo and sets a preference to make sure it is not shown again. */
     @Override
     public void dismiss(Callback<String> itemRemovedCallback) {
@@ -188,10 +193,5 @@ public class SignInPromo extends OptionalLeaf
         protected int selectBackground(boolean hasCardAbove, boolean hasCardBelow) {
             return R.drawable.ntp_signin_promo_card_single;
         }
-
-        @Override
-        public boolean isDismissable() {
-            return true;
-        }
     }
 }