[breadcrumb] Add aria-label to the elider button

Define i18n string "More sub-folders...", and use it as the aria-label
of the breadcrumb elider button.

Tbr: Lucino
Bug: 1035691
Change-Id: Iedcd9e65b56268108f81f40d3430c32475dded5e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2096324Reviewed-by: Noel Gordon <noel@chromium.org>
Commit-Queue: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748952}

chrome/browser/chromeos/file_manager/file_manager_string_util.cc

@@ -887,6 +887,8 @@ std::unique_ptr<base::DictionaryValue> GetFileManagerStrings() {
   SET_STRING("GRID_VIEW_FOLDERS_TITLE",
              IDS_FILE_BROWSER_GRID_VIEW_FOLDERS_TITLE);
   SET_STRING("GRID_VIEW_FILES_TITLE", IDS_FILE_BROWSER_GRID_VIEW_FILES_TITLE);
+  SET_STRING("LOCATION_BREADCRUMB_ELIDER_BUTTON_LABEL",
+             IDS_FILE_BROWSER_LOCATION_BREADCRUMB_ELIDER_BUTTON_LABEL);
 #undef SET_STRING
 
   dict->SetString(

ui/chromeos/file_manager_strings.grdp

@@ -1405,6 +1405,9 @@
   <message name="IDS_FILE_BROWSER_GRID_VIEW_FILES_TITLE" desc="Title dislayed in Grid View above the files.">
     Files
   </message>
+  <message name="IDS_FILE_BROWSER_LOCATION_BREADCRUMB_ELIDER_BUTTON_LABEL" desc="Label for the breadcrumb sub-folder elider button in the Files app folder location line.">
+    More sub-folders...
+  </message>
 
 <!-- Common for Audio player and Media player -->
   <message name="IDS_MEDIA_PLAYER_PLAY_BUTTON_LABEL" desc="Label for the Play button of media players (audio player / video player).">

ui/chromeos/file_manager_strings_grdp/IDS_FILE_BROWSER_LOCATION_BREADCRUMB_ELIDER_BUTTON_LABEL.png.sha1

+e9365c70d882e8106aa7ce8199588c4b42b1a1ba
\ No newline at end of file

ui/file_manager/file_manager/foreground/js/ui/breadcrumb.js

@@ -142,7 +142,8 @@ const breadCrumbTemplate = `
 
   <button id='first'></button>
   <span class='caret' hidden></span>
-  <button elider aria-haspopup='menu' aria-expanded='false'>
+  <button elider aria-haspopup='menu' aria-expanded='false'
+      aria-label='$i18n{LOCATION_BREADCRUMB_ELIDER_BUTTON_LABEL}'>
     <span elider></span>
   </button>
   <span class='caret' hidden></span>