Enable surprise me wallpaper for new profiles.

chrome/browser/resources/chromeos/wallpaper_manager/js/event_page.js

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 var WALLPAPER_PICKER_WIDTH = 574;
 var WALLPAPER_PICKER_HEIGHT = 420;
+var SURPRISE_ME_ALARM_NAME = 'DefaultEnableSurpriseMe';
 
 var wallpaperPickerWindow;
 
 var surpriseWallpaper = null;
 
 function SurpriseWallpaper() {
 }
 
 /**
  * Gets SurpriseWallpaper instance. In case it hasn't been initialized, a new
@@ skipping 247 matching lines @@
           WallpaperUtil.setOnlineWallpaper(newValue.url, newValue.layout,
             function() {}, function() {});
         }
         WallpaperUtil.saveToStorage(Constants.AccessLocalWallpaperInfoKey,
                                     newValue, false);
       }
     });
   }
 });
 
-chrome.alarms.onAlarm.addListener(function() {
-  SurpriseWallpaper.getInstance().next();
+chrome.alarms.onAlarm.addListener(function(alarm) {
+  if (alarm.name === SURPRISE_ME_ALARM_NAME) {
+    Constants.WallpaperSyncStorage.get(Constants.AccessSurpriseMeEnabledKey,
+                                        function(items) {
+      if (!items.hasOwnProperty(Constants.AccessSurpriseMeEnabledKey)) {
+        WallpaperUtil.saveToStorage(Constants.AccessSurpriseMeEnabledKey,
+                                    true, true);
+      }
+    });
+  } else {
+    SurpriseWallpaper.getInstance().next();
+  }
 });
+
+/**
+ * Enables surprise me wallpaper iff it has not already been configured.
+ */
+chrome.wallpaperPrivate.onRequestEnableSurpriseMe.addListener(function() {
+  chrome.alarms.create(SURPRISE_ME_ALARM_NAME, {delayInMinutes: 5});
+});