Move all wallpaper file loading and decoding from DesktopBackgroundController to WallpaperManager.

ash/test/ash_test_helper.cc

Index: ash/test/ash_test_helper.cc
diff --git a/ash/test/ash_test_helper.cc b/ash/test/ash_test_helper.cc
index f66c6ce3907635d48efa4624f8a965057f408a22..75034c5bc51d72f0de21b48ff8e672a7c3c5fc8d 100644
--- a/ash/test/ash_test_helper.cc
+++ b/ash/test/ash_test_helper.cc
@@ -30,6 +30,10 @@
 #include "ui/keyboard/keyboard.h"
 #endif
 
+#if defined(OS_WIN)
+#include "base/win/windows_version.h"
+#endif
+
 #if defined(USE_X11)
 #include "ui/aura/window_tree_host_x11.h"
 #endif
@@ -147,5 +151,23 @@ aura::Window* AshTestHelper::CurrentContext() {
   return root_window;
 }
 
+// static
+bool AshTestHelper::SupportsMultipleDisplays() {
+#if defined(OS_WIN)
+  return base::win::GetVersion() < base::win::VERSION_WIN8;
+#else
+  return true;
+#endif
+}
+
+// static
+bool AshTestHelper::SupportsHostWindowResize() {
+#if defined(OS_WIN)
+  return base::win::GetVersion() < base::win::VERSION_WIN8;
+#else
+  return true;
+#endif
+}
+
 }  // namespace test
 }  // namespace ash