Preload default wallpaper.

chrome/browser/chromeos/login/wallpaper_manager.cc

Index: chrome/browser/chromeos/login/wallpaper_manager.cc
diff --git a/chrome/browser/chromeos/login/wallpaper_manager.cc b/chrome/browser/chromeos/login/wallpaper_manager.cc
index 1543c1e06c49f1ac87500d5e1bb3bb7c1851281f..8d09380068eb7592a2bba4953c1226eeef7687b0 100644
--- a/chrome/browser/chromeos/login/wallpaper_manager.cc
+++ b/chrome/browser/chromeos/login/wallpaper_manager.cc
@@ -102,7 +102,7 @@ void WallpaperManager::AddObservers() {
   system::TimezoneSettings::GetInstance()->AddObserver(this);
 }
 
-void WallpaperManager::CacheIfCustomWallpaper(const std::string& email) {
+void WallpaperManager::CacheUserWallpaper(const std::string& email) {
   User::WallpaperType type;
   int index;
   base::Time date;
@@ -114,6 +114,9 @@ void WallpaperManager::CacheIfCustomWallpaper(const std::string& email) {
     wallpaper_loader_->Start(wallpaper_path, 0,
                              base::Bind(&WallpaperManager::CacheWallpaper,
                                         weak_factory_.GetWeakPtr(), email));
+  } else {
+    ash::Shell::GetInstance()->desktop_background_controller()->
+        TriggerCacheDefaultWallpaper(index);
   }
 }