[Nearby] Change Data Usage settings strings

The data usage setting was showing the current value and a description.
Now it shows the name of the setting and the current value to match the
way other settings are shown. E.g. instead of
  Mobile data
  May incur mobile data charges
show
  Data Usage
  Mobile data
https://screenshot.googleplex.com/AaDrHHDc7hMZnTs.png

In the data usage dialog, change the confirm button from "Update" to
"Done".

Fixed: 1168289, 1168287
Change-Id: I7bec6416909a4f4e3b95a76026e242eccf430e2b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2643568Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Reviewed-by: James Vecore <vecore@google.com>
Commit-Queue: Curt Clemens <cclem@google.com>
Cr-Commit-Position: refs/heads/master@{#846171}

chrome/app/shared_settings_strings.grdp

@@ -124,7 +124,7 @@
     Edit
   </message>
   <message name="IDS_SETTINGS_NEARBY_SHARE_UPDATE_DATA_USAGE" desc="Label for the button that allows a user to confirm their choice of data usage setting for the Nearby Share feature.">
-    Update
+    Done
   </message>
   <message name="IDS_SETTINGS_NEARBY_SHARE_DATA_USAGE_DIALOG_TITLE" desc="Title for the dialog where a user can select the data usage setting for the Nearby Share feature.">
     Data usage

chrome/app/shared_settings_strings_grdp/IDS_SETTINGS_NEARBY_SHARE_UPDATE_DATA_USAGE.png.sha1

-3989dd9c90c1742c7c9aa9c14d603ca3ae5bab12
\ No newline at end of file
+0307ae5a2ae4ccf3e61deea2c967c3172254a2fe
\ No newline at end of file

chrome/browser/resources/settings/chromeos/nearby_share_page/nearby_share_subpage.html

@@ -172,10 +172,10 @@
     <div class="settings-box two-line">
       <div class="start">
         <div aria-hidden="true">
-          [[getDataUsageLabel_(prefs.nearby_sharing.data_usage.value)]]
+          $i18n{nearbyShareDataUsageDialogTitle}
         </div>
         <div aria-hidden="true" class="secondary">
-          [[getDataUsageSubLabel_(prefs.nearby_sharing.data_usage.value)]]
+          [[getDataUsageLabel_(prefs.nearby_sharing.data_usage.value)]]
         </div>
       </div>
       <cr-button id="editDataUsageButton" on-click="onDataUsageTap_"