Add option to SkDecodingImageGenerator to require unpremul.

src/images/SkDecodingImageGenerator.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 SkDecodingImageGenerator_DEFINED
 #define SkDecodingImageGenerator_DEFINED
 
@@ skipping 22 matching lines @@
      *
      *  @param fDitherImage Set to true if the the decoder should try to
      *         dither the resulting image when decoding to a smaller
      *         color-space.  The default is true.
      *
      *  @param fRequestedColorType If not given, then use whichever
      *         config the decoder wants.  Else try to use this color
      *         type.  If the decoder won't support this color type,
      *         SkDecodingImageGenerator::Create will return
      *         NULL. kIndex_8_SkColorType is not supported.
+     *
+     *  @param fRequireUnpremul If true, the decoder will attempt to
+     *         decode without premultiplying the alpha. If it cannot,
+     *         the pixels will be set to NULL.
      */
     struct Options {
         Options()
             : fSampleSize(1)
             , fDitherImage(true)
             , fUseRequestedColorType(false)
-            , fRequestedColorType() { }
+            , fRequestedColorType()
+            , fRequireUnpremul(false) { }
         Options(int sampleSize, bool dither)
             : fSampleSize(sampleSize)
             , fDitherImage(dither)
             , fUseRequestedColorType(false)
-            , fRequestedColorType() { }
+            , fRequestedColorType()
+            , fRequireUnpremul(false) { }
         Options(int sampleSize, bool dither, SkColorType colorType)
             : fSampleSize(sampleSize)
             , fDitherImage(dither)
             , fUseRequestedColorType(true)
-            , fRequestedColorType(colorType) { }
+            , fRequestedColorType(colorType)
+            , fRequireUnpremul(false) { }
+         Options(int sampleSize, bool dither, SkColorType colorType,
+                 bool requireUnpremul)
+            : fSampleSize(sampleSize)
+            , fDitherImage(dither)
+            , fUseRequestedColorType(true)
+            , fRequestedColorType(colorType)
+            , fRequireUnpremul(requireUnpremul) { }
         const int         fSampleSize;
         const bool        fDitherImage;
         const bool        fUseRequestedColorType;
         const SkColorType fRequestedColorType;
+        const bool        fRequireUnpremul;
     };
 
     /**
      *  These two functions return a SkImageGenerator that calls into
      *  SkImageDecoder.  They return NULL on failure.
      *
      *  The SkData version of this function is preferred.  If the stream
      *  has an underlying SkData (such as a SkMemoryStream) pass that in.
      *
      *  This object will unref the stream when done or on failure.  Since
@@ skipping 33 matching lines @@
 //         SkDecodingImageGenerator::Create(
 //             data, SkDecodingImageGenerator::Options()), dst, NULL);
 //  }
 //  bool install_stream(SkStreamRewindable* stream, SkBitmap* dst) {
 //     return SkInstallDiscardablePixelRef(
 //         SkDecodingImageGenerator::Create(
 //             stream, SkDecodingImageGenerator::Options()), dst, NULL);
 //  }
 
 #endif  // SkDecodingImageGenerator_DEFINED