add ImageGenerator::NewFromData to porting layer

include/core/SkImage.h

Index: include/core/SkImage.h
diff --git a/include/core/SkImage.h b/include/core/SkImage.h
index 5ce32eafb7adbb4cd799358250944fb84808452c..9cc26ed4be3dff13d9a2986a3785ca4ce448d4cb 100644
--- a/include/core/SkImage.h
+++ b/include/core/SkImage.h
@@ -63,6 +63,15 @@ public:
      */
     static SkImage* NewFromGenerator(SkImageGenerator*);
 
+    /**
+     *  Construct a new SkImage based on the specified encoded data. Returns NULL on failure,
+     *  which can mean that the format of the encoded data was not recognized/supported.
+     *
+     *  Regardless of success or failure, the caller is responsible for managing their ownership
+     *  of the data.
+     */
+    static SkImage* NewFromData(SkData* data);
+
     int width() const { return fWidth; }
     int height() const { return fHeight; }
     uint32_t uniqueID() const { return fUniqueID; }