Upgrade SkSpecialImage to have getTextureRef & getROPixels entry points

src/gpu/GrLayerHoister.cpp

Index: src/gpu/GrLayerHoister.cpp
diff --git a/src/gpu/GrLayerHoister.cpp b/src/gpu/GrLayerHoister.cpp
index dd8a48547ac0c311e9d097e5f0531fbc59a459a4..9a2be0be6044034af55b8e2b3bc8c68e1715144e 100644
--- a/src/gpu/GrLayerHoister.cpp
+++ b/src/gpu/GrLayerHoister.cpp
@@ -318,8 +318,9 @@ void GrLayerHoister::FilterLayer(GrContext* context,
         return;
     }
 
-    SkASSERT(result->peekTexture());
-    layer->setTexture(result->peekTexture(), result->subset(), false);
+    SkASSERT(result->isTextureBacked());
+    SkAutoTUnref<GrTexture> texture(result->asTextureRef(context));
+    layer->setTexture(texture, result->subset(), false);
     layer->setOffset(offset);
 }