Adjust the alpha type for pixelRefs.

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 102 matching lines @@
     return width * SkColorTypeBytesPerPixel(ct);
 }
 
 static inline bool SkColorTypeIsValid(unsigned value) {
     return value <= kLastEnum_SkColorType;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 /**
+ *  Return true if alphaType is supported by colorType. If there is a canonical
+ *  alphaType for this colorType, return it in canonical.
+ */
+bool SkColorTypeValidateAlphaType(SkColorType colorType, SkAlphaType alphaType,
+                                  SkAlphaType* canonical = NULL);
+
+///////////////////////////////////////////////////////////////////////////////
+
+/**
  *  Describe an image's dimensions and pixel type.
  */
 struct SkImageInfo {
     int         fWidth;
     int         fHeight;
     SkColorType fColorType;
     SkAlphaType fAlphaType;
 
     static SkImageInfo Make(int width, int height, SkColorType ct, SkAlphaType at) {
         SkImageInfo info = {
@@ skipping 106 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