[Touchless] Guard against parsing null/empty strings.

Bug: 955174
Change-Id: Id6a01cb3f237a088add8062717d8354b77cefa52
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1577932Reviewed-by: Theresa <twellington@chromium.org>
Commit-Queue: Sky Malice <skym@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653579}

chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPage.java

@@ -622,7 +622,10 @@ public class NewTabPage implements NativePage, InvalidationAwareThumbnailProvide
         if (tab.getWebContents() == null) return defaultValue;
 
         String stringValue = getStringFromNavigationEntry(tab, key);
-
+        if (stringValue == null || stringValue.isEmpty()) {
+            return RecyclerView.NO_POSITION;
+        }
+        
         try {
             return Integer.parseInt(stringValue);
         } catch (NumberFormatException e) {