Eliminate ash::internal namespace

ash/desktop_background/wallpaper_resizer_unittest.cc

Index: ash/desktop_background/wallpaper_resizer_unittest.cc
diff --git a/ash/desktop_background/wallpaper_resizer_unittest.cc b/ash/desktop_background/wallpaper_resizer_unittest.cc
index 12adaf3831f42885edabaa6291e1a81539fbe6d0..240dc8e048565c758ad41dc455f8747aa2d3be74 100644
--- a/ash/desktop_background/wallpaper_resizer_unittest.cc
+++ b/ash/desktop_background/wallpaper_resizer_unittest.cc
@@ -55,7 +55,6 @@ bool IsColor(const gfx::ImageSkia& image, const uint32_t expect) {
 }  // namespace
 
 namespace ash {
-namespace internal {
 
 class WallpaperResizerTest : public testing::Test,
                              public WallpaperResizerObserver {
@@ -156,5 +155,4 @@ TEST_F(WallpaperResizerTest, ImageId) {
   EXPECT_EQ(WallpaperResizer::GetImageId(image), resizer.original_image_id());
 }
 
-}  // namespace internal
 }  // namespace ash