Handle IME selection focus for ENABLE_DEVICE_SEARCH

Bug: 162861289
Change-Id: I15e4eae09be2aa9f89a5157fd74c95e91e64bc53

src/com/android/launcher3/allapps/PluginHeaderRow.java

@@ -83,4 +83,9 @@ public class PluginHeaderRow implements FloatingHeaderRow {
     public Class<PluginHeaderRow> getTypeClass() {
         return PluginHeaderRow.class;
     }
+
+    @Override
+    public View getFocusedChild() {
+        return null;
+    }
 }