Correct External protocol prompt checkbox text

The current text of the checkbox is "Always open these types of links in
the associated app" but this string does not make sense as the wrong
element is plural. A link has only one type, and the checkbox only acts
on one type.

Change text to "Always open links of this type in the associated app".

Bug: 1017841
Change-Id: Ibb5ae5b52d84c068144ef1bb974dd11ebb11b8f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1879771Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Eric Lawrence [MSFT] <ericlaw@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#709195}

chrome/app/generated_resources.grd

@@ -7457,7 +7457,7 @@ the Bookmarks menu.">
           Cancel
         </message>
         <message name="IDS_EXTERNAL_PROTOCOL_CHECKBOX_TEXT" desc="Checkbox to ask the user whether they would like their decision remembered.">
-          Always open these types of links in the associated app
+          Always open links of this type in the associated app
         </message>
       </if>
       <if expr="chromeos">