Apply default wallpaper from customization manifest.

ash/desktop_background/desktop_background_controller.h

Index: ash/desktop_background/desktop_background_controller.h
diff --git a/ash/desktop_background/desktop_background_controller.h b/ash/desktop_background/desktop_background_controller.h
index 219e3c82f360e2cc2fb2be7ed350342b5af7d3d5..21c830f92ca52df313597a2927d0dab8aa583052 100644
--- a/ash/desktop_background/desktop_background_controller.h
+++ b/ash/desktop_background/desktop_background_controller.h
@@ -25,6 +25,9 @@ class Window;
 
 namespace ash {
 
+// -1
+extern const int ASH_EXPORT kInvalidResourceID;
+
 enum WallpaperLayout {
   // Center the wallpaper on the desktop without scaling it. The wallpaper
   // may be cropped.
@@ -37,6 +40,9 @@ enum WallpaperLayout {
   WALLPAPER_LAYOUT_STRETCH,
   // Tile the wallpaper over the background without scaling it.
   WALLPAPER_LAYOUT_TILE,
+  // This is a special value for WallpaperIsAlreadyLoaded()
+  // meaning "do not compare layouts".
+  WALLPAPER_LAYOUT_UNKNOWN,
 };
 
 const SkColor kLoginWallpaperColor = 0xFEFEFE;
@@ -108,18 +114,19 @@ class ASH_EXPORT DesktopBackgroundController
   // maximum width of all displays, and the maximum height of all displays.
   static gfx::Size GetMaxDisplaySizeInNative();
 
- private:
-  friend class DesktopBackgroundControllerTest;
-  //  friend class chromeos::WallpaperManagerBrowserTestDefaultWallpaper;
-  FRIEND_TEST_ALL_PREFIXES(DesktopBackgroundControllerTest, GetMaxDisplaySize);
-
   // Returns true if the specified wallpaper is already stored
   // in |current_wallpaper_|.
   // If |image| is NULL, resource_id is compared.
+  // If |layout| == WALLPAPER_LAYOUT_UNKNOWN, layout is ignored.
   bool WallpaperIsAlreadyLoaded(const gfx::ImageSkia* image,
                                 int resource_id,
                                 WallpaperLayout layout) const;
 
+ private:
+  friend class DesktopBackgroundControllerTest;
+  //  friend class chromeos::WallpaperManagerBrowserTestDefaultWallpaper;
+  FRIEND_TEST_ALL_PREFIXES(DesktopBackgroundControllerTest, GetMaxDisplaySize);
+
   // Creates view for all root windows, or notifies them to repaint if they
   // already exist.
   void SetDesktopBackgroundImageMode();