Add aria label to Download settings

Make the Chrome settings Download page only one stop in ChromeVox.

Video: http://crbug/986417#c18

Fixed: 986417
Change-Id: I13da58bf74c1aa0c8dc0cb0059668325e3ce9f8c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2462385Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Commit-Queue: Gavin Williams <gavinwill@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815771}

chrome/browser/resources/settings/downloads_page/downloads_page.html

@@ -5,8 +5,8 @@
     </style>
     <div class="cr-row first">
       <div class="flex cr-padded-text">
-        <div>$i18n{downloadLocation}</div>
-        <div class="secondary" id="defaultDownloadPath">
+        <div id="locationLabel" aria-hidden="true">$i18n{downloadLocation}</div>
+        <div class="secondary" id="defaultDownloadPath" aria-hidden="true">
 <if expr="not chromeos">
           [[prefs.download.default_directory.value]]
 </if>
@@ -18,6 +18,7 @@
       <div class="separator"></div>
       <controlled-button id="changeDownloadsPath"
           label="$i18n{changeDownloadLocation}"
+          aria-labelledby="locationLabel defaultDownloadPath"
           on-click="selectDownloadLocation_"
           pref="[[prefs.download.default_directory]]"
           end-justified>