Add an option to create unpremultiplied bitmaps.

include/core/SkImageDecoder.h

Index: include/core/SkImageDecoder.h
diff --git a/include/core/SkImageDecoder.h b/include/core/SkImageDecoder.h
index 5ef569047b81087ccc728ef8c486d51e648593d5..d41d9880b102a91e5ef23f4e79e93113f00e02dd 100644
--- a/include/core/SkImageDecoder.h
+++ b/include/core/SkImageDecoder.h
@@ -82,6 +82,19 @@ public:
         fPreferQualityOverSpeed = qualityOverSpeed;
     }
 
+    /** Set to true if the decoder should return a bitmap with unpremultiplied
+        colors. The decoder is free to ignore this request. The default is
+        false, meaning the resulting bitmap will have its colors premultiplied.
+    */
+    void setRequestUnpremultipliedColors(bool request) {
+        fRequestUnpremultipliedColors = request;
+    }
+
+    /** Returns true if the decoder should try to return a bitmap with unpremultiplied
+        colors.
+    */
+    bool getRequestUnpremultipliedColors() const { return fRequestUnpremultipliedColors; }
+
     /** \class Peeker
 
         Base class for optional callbacks to retrieve meta/chunk data out of
@@ -433,6 +446,7 @@ private:
     bool                    fUsePrefTable;
     mutable bool            fShouldCancelDecode;
     bool                    fPreferQualityOverSpeed;
+    bool                    fRequestUnpremultipliedColors;
 };
 
 /** Calling newDecoder with a stream returns a new matching imagedecoder