[Files.app a11y] Add missing a11y labels into buttons

BUG=459695
TEST=manually tested

Review URL: https://codereview.chromium.org/939073002

Cr-Commit-Position: refs/heads/master@{#317049}

chrome/app/chromeos_strings.grdp

@@ -445,9 +445,18 @@ Press any key to continue exploring.
   <message name="IDS_FILE_BROWSER_SHARE_BUTTON_LABEL" desc="Menu item label, showing dialog to share the selected file.">
     Share
   </message>
+  <message name="IDS_FILE_BROWSER_TASKS_BUTTON_LABEL" desc="Label for button that selects a task to open the current file.">
+    Tasks
+  </message>
   <message name="IDS_FILE_BROWSER_CANCEL_SELECTION_BUTTON_LABEL" desc="Label for button that unselects all selected items.">
     Cancel selection
   </message>
+  <message name="IDS_FILE_BROWSER_CHANGE_TO_LISTVIEW_BUTTON_LABEL" desc="Label for button that changes the view mode to 'list view' mode.">
+    List view
+  </message>
+  <message name="IDS_FILE_BROWSER_CHANGE_TO_THUMBNAILVIEW_BUTTON_LABEL" desc="Label for button that changes the view mode to 'thumbnail view' mode.">
+    Thumbnail view
+  </message>
   <message name="IDS_FILE_BROWSER_CLOUD_IMPORT_TITLE" desc="Title of the cloud import feature.">
     Cloud backup
   </message>

chrome/browser/chromeos/extensions/file_manager/private_api_strings.cc

@@ -486,7 +486,12 @@ bool FileManagerPrivateGetStringsFunction::RunSync() {
   SET_STRING("SEARCH_NO_MATCHING_FILES_HTML",
              IDS_FILE_BROWSER_SEARCH_NO_MATCHING_FILES_HTML);
   SET_STRING("SEARCH_TEXT_LABEL", IDS_FILE_BROWSER_SEARCH_TEXT_LABEL);
+  SET_STRING("TASKS_BUTTON_LABEL", IDS_FILE_BROWSER_TASKS_BUTTON_LABEL);
   SET_STRING("SHARE_BUTTON_LABEL", IDS_FILE_BROWSER_SHARE_BUTTON_LABEL);
+  SET_STRING("CHANGE_TO_LISTVIEW_BUTTON_LABEL",
+             IDS_FILE_BROWSER_CHANGE_TO_LISTVIEW_BUTTON_LABEL);
+  SET_STRING("CHANGE_TO_THUMBNAILVIEW_BUTTON_LABEL",
+             IDS_FILE_BROWSER_CHANGE_TO_THUMBNAILVIEW_BUTTON_LABEL);
   SET_STRING("CANCEL_SELECTION_BUTTON_LABEL",
              IDS_FILE_BROWSER_CANCEL_SELECTION_BUTTON_LABEL);
   SET_STRING("SHARE_ERROR", IDS_FILE_BROWSER_SHARE_ERROR);

ui/file_manager/file_manager/foreground/js/ui/directory_tree.js

@@ -535,6 +535,7 @@ VolumeItem.prototype.setupEjectButton_ = function(rowElement) {
     ejectButton.addEventListener(
         'mousedown', function(event) { event.stopPropagation() });
     ejectButton.className = 'root-eject';
+    ejectButton.setAttribute('aria-label', str('UNMOUNT_DEVICE_BUTTON_LABEL'));
     ejectButton.addEventListener('click', function(event) {
       event.stopPropagation();
       var unmountCommand = cr.doc.querySelector('command#unmount');

ui/file_manager/file_manager/foreground/js/ui/file_manager_ui.js

@@ -369,8 +369,12 @@ FileManagerUI.prototype.relayout = function() {
 FileManagerUI.prototype.setCurrentListType = function(listType) {
   this.listContainer.setCurrentListType(listType);
 
-  this.toggleViewButton.classList.toggle(
-      'thumbnail', listType === ListContainer.ListType.DETAIL);
+  var isListView = (listType === ListContainer.ListType.DETAIL);
+  this.toggleViewButton.classList.toggle('thumbnail', isListView);
+
+  var label = isListView ? str('CHANGE_TO_THUMBNAILVIEW_BUTTON_LABEL') :
+                           str('CHANGE_TO_LISTVIEW_BUTTON_LABEL');
+  this.toggleViewButton.setAttribute('aria-label', label);
   this.relayout();
 };
 

ui/file_manager/file_manager/main.html

@@ -319,7 +319,8 @@
     <div class="dialog-header">
       <div id="location-breadcrumbs" class="breadcrumbs"></div>
       <div id="cancel-selection-button-wrapper">
-        <paper-button id="cancel-selection-button" tabindex="-1">
+        <paper-button id="cancel-selection-button" tabindex="-1"
+              i18n-values="aria-label:CANCEL_SELECTION_BUTTON_LABEL">
           <span class="icon-arrow-back"></span>
           <span i18n-content="CANCEL_SELECTION_BUTTON_LABEL"></span>
         </paper-button>
@@ -327,15 +328,18 @@
       <div id="files-selected-label"></div>
       <div class="spacer"></div>
       <button id="tasks" class="combobutton" menu="#tasks-menu"
-              tabindex="7">
+              tabindex="7"
+              i18n-values="aria-label:TASKS_BUTTON_LABEL">
         <paper-ripple fit></paper-ripple>
       </button>
-      <button id="search-button" class="icon-button" tabindex="8">
+      <button id="search-button" class="icon-button" tabindex="8"
+              i18n-values="aria-label:SEARCH_TEXT_LABEL">
         <paper-ripple fit class="recenteringTouch circle"></paper-ripple>
       </button>
       <div id="search-box">
         <paper-input-decorator i18n-values="label:SEARCH_TEXT_LABEL">
-          <input is="core-input" type="search" tabindex="-1" i18n-values="aria-label:SEARCH_TEXT_LABEL">
+          <input is="core-input" type="search" tabindex="-1"
+                 i18n-values="aria-label:SEARCH_TEXT_LABEL">
         </paper-input-decorator>
         <button class="clear" tabindex="-1"></button>
       </div>
@@ -365,7 +369,8 @@
         <core-icon icon="arrow-drop-down"></core-icon>
         <paper-ripple fit class="recenteringTouch circle"></paper-ripple>
       </button>
-      <button id="view-button" class="icon-button" tabindex="13">
+      <button id="view-button" class="icon-button" tabindex="13"
+              i18n-values="aria-label:CHANGE_TO_THUMBNAILVIEW_BUTTON_LABEL">
         <paper-ripple fit class="recenteringTouch circle"></paper-ripple>
       </button>
       <button id="gear-button" class="icon-button" tabindex="14" menu="#gear-menu"