change offset to xy for pixelref subsetting

BUG=
R=scroggo@google.com

Review URL: https://codereview.chromium.org/105893012

git-svn-id: http://skia.googlecode.com/svn/trunk@12958 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tools/PictureRenderer.cpp b/tools/PictureRenderer.cpp
index b61288a..53654b9 100644
--- a/tools/PictureRenderer.cpp
+++ b/tools/PictureRenderer.cpp
@@ -340,16 +340,8 @@
     return NULL;
 }
 
-static SkData* encode_bitmap_to_data(size_t* offset, const SkBitmap& bm) {
-    SkPixelRef* pr = bm.pixelRef();
-    if (pr != NULL) {
-        SkData* data = pr->refEncodedData();
-        if (data != NULL) {
-            *offset = bm.pixelRefOffset();
-            return data;
-        }
-    }
-    *offset = 0;
+// the size_t* parameter is deprecated, so we ignore it
+static SkData* encode_bitmap_to_data(size_t*, const SkBitmap& bm) {
     return SkImageEncoder::EncodeData(bm, SkImageEncoder::kPNG_Type, 100);
 }