use colortype instead of config

include/core/SkImageInfo.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkImageInfo_DEFINED
 #define SkImageInfo_DEFINED
 
@@ skipping 147 matching lines @@
         return MakeN32Premul(size.width(), size.height());
     }
 
     static SkImageInfo MakeA8(int width, int height) {
         SkImageInfo info = {
             width, height, kAlpha_8_SkColorType, kPremul_SkAlphaType
         };
         return info;
     }
 
+    static SkImageInfo MakeUnknown(int width, int height) {
+        SkImageInfo info = {
+            width, height, kUnknown_SkColorType, kIgnore_SkAlphaType
+        };
+        return info;
+    }
+
     int width() const { return fWidth; }
     int height() const { return fHeight; }
     SkColorType colorType() const { return fColorType; }
     SkAlphaType alphaType() const { return fAlphaType; }
 
     bool isEmpty() const { return fWidth <= 0 || fHeight <= 0; }
 
     bool isOpaque() const {
         return SkAlphaTypeIsOpaque(fAlphaType);
     }
@@ skipping 35 matching lines @@
 
     bool validRowBytes(size_t rowBytes) const {
         uint64_t rb = sk_64_mul(fWidth, this->bytesPerPixel());
         return rowBytes >= rb;
     }
 
     SkDEBUGCODE(void validate() const;)
 };
 
 #endif