ash: Avoid reloading already-resized custom wallpaper.

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 844730769556dced30e6712ddc87b016093fda18..98a43fe76a42e7855900e76bfe34124e2f424916 100644
--- a/ash/desktop_background/wallpaper_resizer_unittest.cc
+++ b/ash/desktop_background/wallpaper_resizer_unittest.cc
@@ -41,7 +41,9 @@ gfx::ImageSkia CreateTestImage(const gfx::Size& size) {
     }
   }
 
-  return gfx::ImageSkia::CreateFrom1xBitmap(src);
+  gfx::ImageSkia image = gfx::ImageSkia::CreateFrom1xBitmap(src);
+  image.MakeThreadSafe();
+  return image;
 }
 
 bool IsColor(const gfx::ImageSkia& image, const uint32_t expect) {
@@ -74,7 +76,7 @@ class WallpaperResizerTest : public testing::Test,
     resizer->StartResize();
     WaitForResize();
     resizer->RemoveObserver(this);
-    return resizer->wallpaper_image();
+    return resizer->image();
   }
 
   void WaitForResize() {
@@ -141,5 +143,20 @@ TEST_F(WallpaperResizerTest, AllLayoutDifferent) {
   EXPECT_TRUE(IsColor(tile, kExpectedTile));
 }
 
+TEST_F(WallpaperResizerTest, ImageId) {
+  gfx::ImageSkia image = CreateTestImage(
+      gfx::Size(kTestImageWidth, kTestImageHeight));
+
+  // Create a WallpaperResizer and check that it reports an original image ID
+  // both pre- and post-resize that matches the ID returned by GetImageId().
+  WallpaperResizer resizer(image, gfx::Size(10, 20), WALLPAPER_LAYOUT_STRETCH);
+  EXPECT_EQ(WallpaperResizer::GetImageId(image), resizer.original_image_id());
+  resizer.AddObserver(this);
+  resizer.StartResize();
+  WaitForResize();
+  resizer.RemoveObserver(this);
+  EXPECT_EQ(WallpaperResizer::GetImageId(image), resizer.original_image_id());
+}
+
 }  // namespace internal
 }  // namespace ash