Add freeze tab menu option

  Adds a freeze tab menu option hidden behind about:debug for now.

Change-Id: I1b321de6a5dbcb13e87f6e658439f727970b0e4f
diff --git a/res/values/strings.xml b/res/values/strings.xml
index ae28023..e51538c 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -235,6 +235,9 @@
     <string name="copy_page_url">Copy page url</string>
     <!-- Menu item -->
     <string name="share_page">Share page</string>
+    <!-- Menu item to freeze a tab. This will make a view-only
+            snapshot of the page in a new tab. [CHAR LIMIT=50] -->
+    <string name="menu_freeze_tab">Freeze tab</string>
     <!-- Menu item for saving a page. [CHAR LIMIT=30] -->
     <string name="menu_save_webarchive">Save page</string>
     <!-- Toast informing the user that the page has been saved. [CHAR LIMIT=50] -->