Don't scale mask image for new tab button.

ui/gfx/image/image_skia_operations.cc

Index: ui/gfx/image/image_skia_operations.cc
diff --git a/ui/gfx/image/image_skia_operations.cc b/ui/gfx/image/image_skia_operations.cc
index b07993ddffacea8e5bb7b8e19e4cd51625147658..b0940d127368252ef718c13f691a60beaa369939 100644
--- a/ui/gfx/image/image_skia_operations.cc
+++ b/ui/gfx/image/image_skia_operations.cc
@@ -167,7 +167,6 @@ class MaskedImageSource : public gfx::ImageSkiaSource {
   virtual ImageSkiaRep GetImageForScale(ui::ScaleFactor scale_factor) OVERRIDE {
     ImageSkiaRep rgb_rep = rgb_.GetRepresentation(scale_factor);
     ImageSkiaRep alpha_rep = alpha_.GetRepresentation(scale_factor);
-    MatchScale(&rgb_rep, &alpha_rep);
     return ImageSkiaRep(SkBitmapOperations::CreateMaskedBitmap(
         rgb_rep.sk_bitmap(), alpha_rep.sk_bitmap()),
                         rgb_rep.scale_factor());