Some cleanup of WallpaperManager.

chrome/browser/chromeos/login/wallpaper_manager_browsertest.cc

Index: chrome/browser/chromeos/login/wallpaper_manager_browsertest.cc
diff --git a/chrome/browser/chromeos/login/wallpaper_manager_browsertest.cc b/chrome/browser/chromeos/login/wallpaper_manager_browsertest.cc
index 821fd98f6ad4d40ae2d3151b922a55b8d1423ae2..76f53f9376ce3ddffd97063b80d239996a64375a 100644
--- a/chrome/browser/chromeos/login/wallpaper_manager_browsertest.cc
+++ b/chrome/browser/chromeos/login/wallpaper_manager_browsertest.cc
@@ -143,6 +143,10 @@ class WallpaperManagerBrowserTest : public InProcessBrowserTest,
     return WallpaperManager::Get()->loaded_wallpapers();
   }
 
+  void ClearDisposableWallpaperCache() {
+    WallpaperManager::Get()->ClearDisposableWallpaperCache();
+  }
+
   DesktopBackgroundController* controller_;
   PrefService* local_state_;
 
@@ -244,7 +248,7 @@ IN_PROC_BROWSER_TEST_P(WallpaperManagerBrowserTest,
   wallpaper_manager->SetUserWallpaperNow(kTestUser1);
   WaitAsyncWallpaperLoadFinished();
   EXPECT_EQ(1, LoadedWallpapers());
-  wallpaper_manager->ClearDisposableWallpaperCache();
+  ClearDisposableWallpaperCache();
 
   // Change wallpaper to a custom wallpaper.
   std::string id = base::Int64ToString(base::Time::Now().ToInternalValue());