allow an extra option on attachments (in bar and tile UI)

Bug: 7659807

Change-Id: I4c1294d2ba772a70139e0b37429b17bc6096cafd
diff --git a/res/values/strings.xml b/res/values/strings.xml
index 0c29b53..d1a493c 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -223,6 +223,8 @@
     <string name="install_attachment">Install</string>
     <!-- Read email screen, button name. Redownload an attachment [CHAR LIMIT=20]-->
     <string name="download_again">Download again</string>
+    <!-- A supplemental option on attachments for apps to override. This string intentionally blank here. [CHAR LIMIT=20] -->
+    <string name="attachment_extra_option1" translatable="false"></string>
     <!-- Dialog box title [CHAR LIMIT=30] -->
     <string name="more_info_attachment">Info</string>
     <!-- Dialog box message, displayed when we could not view an attachment. [CHAR LIMIT=200]-->