Apply default wallpaper from customization manifest.

ash/desktop_background/desktop_background_controller.cc

Index: ash/desktop_background/desktop_background_controller.cc
diff --git a/ash/desktop_background/desktop_background_controller.cc b/ash/desktop_background/desktop_background_controller.cc
index fe111c05e098aabce876793c002f18a606ee2336..02ef5d79c28da360c9cb970c83edf2c53e5a41ef 100644
--- a/ash/desktop_background/desktop_background_controller.cc
+++ b/ash/desktop_background/desktop_background_controller.cc
@@ -43,6 +43,8 @@ const int kWallpaperReloadDelayMs = 2000;
 
 }  // namespace
 
+const int kInvalidResourceID = -1;
+
 DesktopBackgroundController::DesktopBackgroundController()
     : locked_(false),
       desktop_background_mode_(BACKGROUND_NONE),
@@ -198,7 +200,9 @@ bool DesktopBackgroundController::WallpaperIsAlreadyLoaded(
   if (!current_wallpaper_.get())
     return false;
 
-  if (layout != current_wallpaper_->layout())
+  // Do not compare layouts if WALLPAPER_LAYOUT_UNKNOWN passed.
+  if (WALLPAPER_LAYOUT_UNKNOWN != layout &&
+      layout != current_wallpaper_->layout())
     return false;
 
   if (image) {