[cros] Update wallpaper when displaying Gaia frame.

chrome/browser/resources/chromeos/login/user_pod_row.js

 // Copyright (c) 2012 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.
 
 /**
  * @fileoverview User pod row implementation.
  */
 
 cr.define('login', function() {
   /**
@@ skipping 408 matching lines @@
     // True if user pod has been activated with keyboard.
     // In case of activation with keyboard we delay wallpaper change.
     keyboardActivated_: false,
 
     // Focused pod.
     focusedPod_: undefined,
 
     // Activated pod, i.e. the pod of current login attempt.
     activatedPod_: undefined,
 
+    // Pod that was most recently focused, if any.
+    lastFocusedPod_: undefined,
+
     // When moving through users quickly at login screen, set a timeout to
     // prevent loading intermediate wallpapers.
     loadWallpaperTimeout_: null,
 
     // Pods whose initial images haven't been loaded yet.
     podsWithPendingImages_: [],
 
     /** @inheritDoc */
     decorate: function() {
       this.style.left = 0;
@@ skipping 150 matching lines @@
     /**
      * Populates pod row with given existing users and start init animation.
      * @param {array} users Array of existing user emails.
      * @param {boolean} animated Whether to use init animation.
      */
     loadPods: function(users, animated) {
       // Clear existing pods.
       this.innerHTML = '';
       this.focusedPod_ = undefined;
       this.activatedPod_ = undefined;
+      this.lastFocusedPod_ = undefined;
 
       // Populate the pod row.
       for (var i = 0; i < users.length; ++i) {
         this.addUserPod(users[i], animated);
       }
       for (var i = 0, pod; pod = this.pods[i]; ++i) {
         this.podsWithPendingImages_.push(pod);
       }
       // Make sure we eventually show the pod row, even if some image is stuck.
       setTimeout(function() {
@@ skipping 51 matching lines @@
         if (hadFocus && this.keyboardActivated_) {
           // Delay wallpaper loading to let user tab through pods without lag.
           this.loadWallpaperTimeout_ = window.setTimeout(
               this.loadWallpaper_.bind(this), WALLPAPER_LOAD_DELAY_MS);
         } else if (!this.firstShown_) {
           // Load wallpaper immediately if there no pod was focused
           // previously, and it is not a boot into user pod list case.
           this.loadWallpaper_();
         }
         this.firstShown_ = false;
-      } else {
-        chrome.send('userDeselected');
+        this.lastFocusedPod_ = podToFocus;
       }
       this.insideFocusPod_ = false;
       this.keyboardActivated_ = false;
     },
 
+    /**
+     * Loads wallpaper for the active user pod, if any.
+     * @private
+     */
     loadWallpaper_: function() {
       if (this.focusedPod_)
-        chrome.send('userSelectedDelayed', [this.focusedPod_.user.username]);
+        chrome.send('loadWallpaper', [this.focusedPod_.user.username]);
     },
 
     /**
+     * Resets wallpaper to the last active user's wallpaper, if any.
+     */
+    loadLastWallpaper: function() {
+      if (this.lastFocusedPod_)
+        chrome.send('loadWallpaper', [this.lastFocusedPod_.user.username]);
+    },
+
+    /**
      * Returns the currently activated pod.
      * @type {UserPod}
      */
     get activatedPod() {
       return this.activatedPod_;
     },
     set activatedPod(pod) {
       if (pod && pod.activate())
         this.activatedPod_ = pod;
     },
@@ skipping 32 matching lines @@
     },
 
     /**
      * Shows signin UI.
      * @param {string} email Email for signin UI.
      */
     showSigninUI: function(email) {
       // Clear any error messages that might still be around.
       Oobe.clearErrors();
       this.disabled = true;
+      this.lastFocusedPod_ = this.getPodWithUsername_(email);
       Oobe.showSigninUI(email);
     },
 
     /**
      * Updates current image of a user.
      * @param {string} username User for which to update the image.
      */
     updateUserImage: function(username) {
       var pod = this.getPodWithUsername_(username);
       if (pod)
@@ skipping 165 matching lines @@
         this.classList.remove('images-loading');
         chrome.send('userImagesLoaded');
       }
     }
   };
 
   return {
     PodRow: PodRow
   };
 });