Delay wallpaper load by 2 * average wallpaper load time.

chrome/browser/chromeos/login/wallpaper_manager.h

Index: chrome/browser/chromeos/login/wallpaper_manager.h
diff --git a/chrome/browser/chromeos/login/wallpaper_manager.h b/chrome/browser/chromeos/login/wallpaper_manager.h
index 3a6a0ffce59eec156a8f06b148e0f9ed6b2f5c08..ac8379cebdb3d9932dc1192cc17e095add62c614 100644
--- a/chrome/browser/chromeos/login/wallpaper_manager.h
+++ b/chrome/browser/chromeos/login/wallpaper_manager.h
@@ -12,6 +12,7 @@
 #include "base/memory/ref_counted_memory.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/time/time.h"
 #include "chrome/browser/chromeos/login/user.h"
@@ -80,6 +81,12 @@ class WallpaperManager: public content::NotificationObserver {
     DISALLOW_COPY_AND_ASSIGN(TestApi);
   };
 
+  class Observer {
+   public:
+    virtual ~Observer() {}
+    virtual void OnWallpaperAnimationFinished(const std::string& email) = 0;
+  };
+
   static WallpaperManager* Get();
 
   WallpaperManager();
@@ -188,6 +195,12 @@ class WallpaperManager: public content::NotificationObserver {
   // current display's resolution.
   void UpdateWallpaper();
 
+  // Adds given observer to the list.
+  void AddObserver(Observer* observer);
+
+  // Removes given observer from the list.
+  void RemoveObserver(Observer* observer);
+
  private:
   friend class TestApi;
   friend class WallpaperManagerBrowserTest;
@@ -306,6 +319,9 @@ class WallpaperManager: public content::NotificationObserver {
                  bool update_wallpaper,
                  const base::FilePath& wallpaper_path);
 
+  // Notify all registed observers.
+  void NotifyAnimationFinished();
+
   // The number of loaded wallpapers.
   int loaded_wallpapers_;
 
@@ -342,6 +358,8 @@ class WallpaperManager: public content::NotificationObserver {
 
   content::NotificationRegistrar registrar_;
 
+  ObserverList<Observer> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(WallpaperManager);
 };