take gr-context parameter to refEncoded, indicating a desire for only gpu-specific formats

src/image/SkImage_Generator.cpp

Index: src/image/SkImage_Generator.cpp
diff --git a/src/image/SkImage_Generator.cpp b/src/image/SkImage_Generator.cpp
index 6671dcd3b142d9d606e6d234c09dc9b9d063e5b7..688b4ffe3ba393c2f5871d605ac1263768ea8610 100644
--- a/src/image/SkImage_Generator.cpp
+++ b/src/image/SkImage_Generator.cpp
@@ -24,7 +24,7 @@ public:
     bool onReadPixels(const SkImageInfo&, void*, size_t, int srcX, int srcY, CachingHint) const override;
     const void* onPeekPixels(SkImageInfo*, size_t* /*rowBytes*/) const override;
     SkImageCacherator* peekCacherator() const override { return fCache; }
-    SkData* onRefEncoded() const override;
+    SkData* onRefEncoded(GrContext*) const override;
     bool isOpaque() const override { return fCache->info().isOpaque(); }
     SkImage* onNewSubset(const SkIRect&) const override;
     bool getROPixels(SkBitmap*, CachingHint) const override;
@@ -66,8 +66,8 @@ const void* SkImage_Generator::onPeekPixels(SkImageInfo* infoPtr, size_t* rowByt
     return NULL;
 }
 
-SkData* SkImage_Generator::onRefEncoded() const {
-    return fCache->refEncoded();
+SkData* SkImage_Generator::onRefEncoded(GrContext* ctx) const {
+    return fCache->refEncoded(ctx);
 }
 
 bool SkImage_Generator::getROPixels(SkBitmap* bitmap, CachingHint chint) const {