[MD settings] theme name shown in sub-label, wallpaper chrome os only

chrome/browser/resources/settings/appearance_page/appearance_page.js

Index: chrome/browser/resources/settings/appearance_page/appearance_page.js
diff --git a/chrome/browser/resources/settings/appearance_page/appearance_page.js b/chrome/browser/resources/settings/appearance_page/appearance_page.js
index d4e2da64705ffca1afbb424a9efea08e7dfba561..c8320e907b5b9f6b5281a8f0e55d4f36683acc4e 100644
--- a/chrome/browser/resources/settings/appearance_page/appearance_page.js
+++ b/chrome/browser/resources/settings/appearance_page/appearance_page.js
@@ -17,6 +17,8 @@
 Polymer({
   is: 'settings-appearance-page',
 
+  behaviors: [I18nBehavior],
+
   properties: {
     /**
      * The current active route.
@@ -99,13 +101,13 @@ Polymer({
         {value: 500, name: '500%'},
       ],
     },
-  },
 
-  behaviors: [
-    I18nBehavior,
-  ],
+    /** @private */
+    themeSublabel_: String,
+  },
 
   observers: [
+    'themeChanged_(prefs.extensions.theme.id.value)',
     'zoomLevelChanged_(defaultZoomLevel_.value)',
   ],
 
@@ -169,6 +171,21 @@ Polymer({
   },
 
   /**
+   * @param {string} themeId The theme ID.
+   * @private
+   */
+  themeChanged_: function(themeId) {
+    if (themeId) {
+      chrome.management.get(themeId,
+          function(info) {
+            this.themeSublabel_ = info.name;
+          }.bind(this));
+    } else {
+      this.themeSublabel_ = this.i18n('chooseFromWebStore');
+    }
+  },
+
+  /**
    * @param {number} percent The integer percentage of the page zoom.
    * @private
    */