Revert of remvoe duplicate impl for SkImageInfo flattening

src/core/SkMaskFilter.cpp

Index: src/core/SkMaskFilter.cpp
diff --git a/src/core/SkMaskFilter.cpp b/src/core/SkMaskFilter.cpp
index adfed4109899dfda776e8b765fa393d02f8309ae..f062f135fdbebbd4f5016bfde05dc0a424e04ccb 100644
--- a/src/core/SkMaskFilter.cpp
+++ b/src/core/SkMaskFilter.cpp
@@ -349,14 +349,10 @@
     if (!result) {
         return false;
     }
-    SkAutoUnref aur(dst);
-
-    SkImageInfo info;
+
     resultBM->setConfig(srcBM.config(), dst->width(), dst->height());
-    if (resultBM->asImageInfo(&info)) {
-        return false;
-    }
-    resultBM->setPixelRef(SkNEW_ARGS(SkGrPixelRef, (info, dst)))->unref();
+    resultBM->setPixelRef(SkNEW_ARGS(SkGrPixelRef, (dst)))->unref();
+    dst->unref();
     return true;
 }