Use "+" icon for FAB

* Reuse the icon for creating a group.
* This change doesn't affect the FAB in Dialer.

Bug 28942847

Change-Id: I111f429c6bef7905c523725c51c5989481ec4538
diff --git a/res/drawable/ic_menu_group_add.xml b/res/drawable/ic_add.xml
similarity index 100%
rename from res/drawable/ic_menu_group_add.xml
rename to res/drawable/ic_add.xml
diff --git a/res/layout/floating_action_button.xml b/res/layout/floating_action_button.xml
index 294d88b..95c76ae 100644
--- a/res/layout/floating_action_button.xml
+++ b/res/layout/floating_action_button.xml
@@ -33,5 +33,5 @@
         android:background="@drawable/floating_action_button"
         android:tint="@color/floating_action_button_icon_color"
         android:contentDescription="@string/action_menu_add_new_contact_button"
-        android:src="@drawable/ic_person_add_24dp"/>
+        android:src="@drawable/ic_add"/>
 </FrameLayout>
\ No newline at end of file