Use LANCZOS3 resize algorithm to generate missing image reps for extension action icons.

ui/gfx/image/image_skia_operations.h

Index: ui/gfx/image/image_skia_operations.h
diff --git a/ui/gfx/image/image_skia_operations.h b/ui/gfx/image/image_skia_operations.h
index 80326b6f2df1ef911eeae43e293c33b897deaec1..10131e691d9e6a87ddb4d0dd4038230644f9fa22 100644
--- a/ui/gfx/image/image_skia_operations.h
+++ b/ui/gfx/image/image_skia_operations.h
@@ -79,10 +79,21 @@ class UI_EXPORT ImageSkiaOperations {
                                  const gfx::Rect& subset_bounds);
 
   // Creates an image by resizing |source| to given |target_dip_size|.
+  // If |source| is missing the representation for a required scale factor, the
+  // representation for the scale factor will be generated by resizing one of
+  // |source|'s existing representations' bitmap to the target pixel size.
+  // The bitmap will be resized using resize method |methd|.
   static ImageSkia CreateResizedImage(const ImageSkia& source,
                                       skia::ImageOperations::ResizeMethod methd,
                                       const Size& target_dip_size);
 
+  // Creates an image which inherits image representations from |source|.
+  // Image representations for the scale factors not containted in |source| are
+  // generated by resizing existing representations using |method|.
+  static ImageSkia CreateImageWithCustomResizeMethod(
+      const ImageSkia& source,
+      skia::ImageOperations::ResizeMethod method);
+
   // Creates an image with drop shadow defined in |shadows| for |source|.
   static ImageSkia CreateImageWithDropShadow(const ImageSkia& source,
                                              const ShadowValues& shadows);