Ensure that the drag image during drag drop operations on Windows is of the correct scale.

ui/base/dragdrop/drag_utils_win.cc

Index: ui/base/dragdrop/drag_utils_win.cc
diff --git a/ui/base/dragdrop/drag_utils_win.cc b/ui/base/dragdrop/drag_utils_win.cc
index 9fedd4202a34ac8e32614fd9de5b9d15a07b8407..a030a5506c26baf1a7169dd7556e518bf1f0f258 100644
--- a/ui/base/dragdrop/drag_utils_win.cc
+++ b/ui/base/dragdrop/drag_utils_win.cc
@@ -18,6 +18,7 @@
 #include "ui/gfx/geometry/size.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/gfx/skbitmap_operations.h"
+#include "ui/gfx/win/dpi.h"
 
 namespace drag_utils {
 
@@ -61,11 +62,23 @@ void SetDragImageOnDataObject(const gfx::ImageSkia& image_skia,
                               const gfx::Vector2d& cursor_offset,
                               ui::OSExchangeData* data_object) {
   DCHECK(data_object && !image_skia.size().IsEmpty());
+
+  // Attempt to find a bitmap matching the current dpi scale, failing which we
+  // fallback to the 1x bitmap.
+  SkBitmap skia_bitmap;
+  if (image_skia.HasRepresentation(gfx::GetDPIScale())) {

[sky, 2015/11/25 23:32:54]

If it doesn't have a rep for the specified dpi, shouldn't you fallback to the
closest one?

[ananta, 2015/11/25 23:37:14]

My bad. We should just use GetRepresentation which does the magic, i.e. returns
the closest matching representation

+    gfx::ImageSkiaRep image_rep_for_scale = image_skia.GetRepresentation(
+        gfx::GetDPIScale());
+    skia_bitmap = image_rep_for_scale.sk_bitmap();
+  } else {
+    skia_bitmap = *image_skia.bitmap();
+  }
+
   // InitializeFromBitmap() doesn't expect an alpha channel and is confused
   // by premultiplied colors, so unpremultiply the bitmap.
   // SetDragImageOnDataObject(HBITMAP) takes ownership of the bitmap.
-  HBITMAP bitmap = CreateHBITMAPFromSkBitmap(
-      SkBitmapOperations::UnPreMultiply(*image_skia.bitmap()));
+  HBITMAP bitmap = CreateHBITMAPFromSkBitmap(SkBitmapOperations::UnPreMultiply(
+      skia_bitmap));
   if (bitmap) {
     // Attach 'bitmap' to the data_object.
     SetDragImageOnDataObject(