Remove uses of SkBitmap::Config (deprecated) from core/ and platform/.

Source/platform/DragImage.cpp

Index: Source/platform/DragImage.cpp
diff --git a/Source/platform/DragImage.cpp b/Source/platform/DragImage.cpp
index 7bc1b92dd4284cb5b45f187aef8620792865c2ce..c075a9221b75b0e142b684005e1ee1f640b6ecfe 100644
--- a/Source/platform/DragImage.cpp
+++ b/Source/platform/DragImage.cpp
@@ -89,9 +89,7 @@ PassOwnPtr<DragImage> DragImage::create(Image* image, RespectImageOrientationEnu
                 destRect = destRect.transposedRect();
 
             SkBitmap skBitmap;
-            skBitmap.setConfig(
-                SkBitmap::kARGB_8888_Config, sizeRespectingOrientation.width(), sizeRespectingOrientation.height());
-            if (!skBitmap.allocPixels())
+            if (!skBitmap.allocN32Pixels(sizeRespectingOrientation.width(), sizeRespectingOrientation.height()))
                 return nullptr;
 
             SkCanvas canvas(skBitmap);