Check index bounds in SessionHistory::getHistoryEntryAt()

embedding/android/GeckoApp.java

@@ -372,9 +372,11 @@ abstract public class GeckoApp
            case R.id.bookmarks:
                Intent intent = new Intent(this, GeckoBookmarks.class);
                SessionHistory.HistoryEntry he = getSessionHistory().getHistoryEntryAt(0);
-               intent.setData(android.net.Uri.parse(he.mUri));
-               intent.putExtra("title", he.mTitle);
-               startActivity(intent);
+               if (he != null) {
+                intent.setData(android.net.Uri.parse(he.mUri));
+                intent.putExtra("title", he.mTitle);
+                startActivity(intent);
+               }
                return true;
            default:
                return super.onOptionsItemSelected(item);

embedding/android/SessionHistory.java

@@ -122,6 +122,8 @@ class SessionHistory
         }
     }
     HistoryEntry getHistoryEntryAt(int index) {
-        return mHistory.get(index);
+        if (index < mHistory.size())
+            return mHistory.get(index);
+        return null;
     }
 }